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1.
Distel MA Vink JM Willemsen G Middeldorp CM Merckelbach HL Boomsma DI 《Behavior genetics》2008,38(1):24-33
Twin studies on fear and phobia suggest moderate genetic effects. However, results are inconclusive regarding the presence
of dominant genetic effects and sex differences. Using an extended twin design, including male and female twins (n = 5,465) and their siblings (n = 1,624), we examined the genetic and environmental influences on blood-injury, social, and agoraphobic fear and investigated
their interaction with sex and age. Data of spouses (n = 708) of twins were used to evaluate assortative mating for the three fear dimensions. Results showed that there was no
assortative mating for blood-injury, social and agoraphobic fear. Resemblance between biological relatives could be explained
by additive and non-additive genetic effects for blood-injury and agoraphobic fear in all participants, and social fear in
participants aged 14–25 years. For social fear in participants aged 26–65 only additive genetic effects were detected. Broad-sense
heritability estimates ranged from 36 to 51% and were similar for men and women.
Edited by John K Hewitt. 相似文献
2.
Heritability estimates of general intelligence in adulthood generally range from 75 to 85%, with all heritability due to additive
genetic influences, while genetic dominance and shared environmental factors are absent, or too small to be detected. These
estimates are derived from studies based on the classical twin design and are based on the assumption of random mating. Yet,
considerable positive assortative mating has been reported for general intelligence. Unmodeled assortative mating may lead
to biased estimates of the relative magnitude of genetic and environmental factors. To investigate the effects of assortative
mating on the estimates of the variance components of intelligence, we employed an extended twin-family design. Psychometric
IQ data were available for adult monozygotic and dizygotic twins, their siblings, the partners of the twins and siblings,
and either the parents or the adult offspring of the twins and siblings (N = 1314). Two underlying processes of assortment were considered: phenotypic assortment and social homogamy. The phenotypic
assortment model was slightly preferred over the social homogamy model, suggesting that assortment for intelligence is mostly
due to a selection of mates on similarity in intelligence. Under the preferred phenotypic assortment model, the variance of
intelligence in adulthood was not only due to non-shared environmental (18%) and additive genetic factors (44%) but also to
non-additive genetic factors (27%) and phenotypic assortment (11%).This non-additive nature of genetic influences on intelligence
needs to be accommodated in future GWAS studies for intelligence. 相似文献
3.
Johnsonet al. (Behav. Genet.
17:1–7, 1987) have interpreted an apparent decline in assortative mating for educational attainment in Hawaii as being a consequence of increased social mobility and increased access to higher education. Data on the educational attainments of adult twin pairs and their spouses from the Virginia twin registry are reported which give no indication of a major decline in the intensity of assortative mating. A previous study of a Norwegian population (Heathet al., Behav. Genet.
15:349–369, 1985), in which an increase in equality of educational opportunity had been documented (Heathet al., Nature
314:734–736, 1985), observed remarkable constancy of the marital correlation for educational attainment. There is thus little evidence that decreases in social inequality in a society lead to a decline in assortative mating.This work was supported in part by NIH Grants GM30250, AG04954 and GM32732 and by ADAMHA Grants AA06781 and MH40828. 相似文献
4.
Biometric studies have shown that happiness is strongly affected by genes. The findings are mainly based on twin data, however,
and the full validity of the results has been debated. To overcome some limitations in classical twin research, we examined
aetiological sources of subjective well-being (SWB), using two independent population-based samples, one including nuclear
families (N = 54,540) and one including twins (N = 6,620). Biometric modelling using R was conducted to test for a data structure implying either non-additive genetic effects
or higher environmental co-twin correlation in MZ than DZ pairs (violation of the EEA). We also estimated non-random mating,
cultural transmission and shared environments specific for regular siblings and twins. Two sets of nested models were fitted
and compared. The best explanatory model shows that family matters for happiness predominantly due to quantitative sex-specific
genetic effects, a moderate spousal correlation and a shared twin environment. Upper limits for broad-sense heritability were
estimated to be 0.33 (females) and 0.36 (males). Our study constitutes the most elaborate biometric study of SWB to date and
illustrates the utility of including responses from multiple types of relatives in quantitative genetic analyses. 相似文献
5.
Findings from many behavioral genetic studies utilizing the classical twin design suggest that genetic and non-shared environmental effects play a significant role in human personality traits. This study
focuses on the methodological advantages of extending the sampling frame to include multiple dyads of relatives. We investigated
the sensitivity of heritability estimates to the inclusion of sibling pairs, mother–child pairs and grandparent–grandchild
pairs from the German Socio-Economic Panel Study in addition to a classical German twin sample consisting of monozygotic- and dizygotic twins. The resulting dataset contained
1.308 pairs, including 202 monozygotic and 147 dizygotic twin pairs, along with 419 sibling pairs, 438 mother–child dyads,
and 102 grandparent–child dyads. This genetically sensitive multi-group design allowed the simultaneous testing of additive
and non-additive genetic, common and specific environmental effects, including cultural transmission and twin-specific environmental
influences. Using manifest and latent modeling of phenotypes (i.e., controlling for measurement error), we compare results
from the extended sample with those from the twin sample alone and discuss implications for future research. 相似文献
6.
We review the literature on the familial resemblance of body mass index (BMI) and other adiposity measures and find strikingly convergent results for a variety of relationships. Results from twin studies suggest that genetic factors explain 50 to 90% of the variance in BMI. Family studies generally report estimates of parent–offspring and sibling correlations in agreement with heritabilities of 20 to 80%. Data from adoption studies are consistent with genetic factors accounting for 20 to 60% of the variation in BMI. Based on data from more than 25,000 twin pairs and 50,000 biological and adoptive family members, the weighted mean correlations are .74 for MZ twins, .32 for DZ twins, .25 for siblings, .19 for parent–offspring pairs, .06 for adoptive relatives, and .12 for spouses. Advantages and disadvantages of twin, family, and adoption studies are reviewed. Data from the Virginia 30,000, including twins and their parents, siblings, spouses, and children, were analyzed using a structural equation model (Stealth) which estimates additive and dominance genetic variance, cultural transmission, assortative mating, nonparental shared environment, and special twin and MZ twin environmental variance. Genetic factors explained 67% of the variance in males and females, of which half is due to dominance. A small proportion of the genetic variance was attributed to the consequences of assortative mating. The remainder of the variance is accounted for by unique environmental factors, of which 7% is correlated across twins. No evidence was found for a special MZ twin environment, thereby supporting the equal environment assumption. These results are consistent with other studies in suggesting that genetic factors play a significant role in the causes of individual differences in relative body weight and human adiposity. 相似文献
7.
Fraternal twin studies on normal subjects have demonstrated low heritability (intra-class correlation coefficient) estimates
for frontal brain regions (r = 0.43). Here we aimed to investigate the relatedness/similarity estimates of the frontal brain regions in fraternal subjects
concordant for Tourette syndrome (TS). We sought to identify regional brain similarities between siblings concordant for TS
as an exploratory step towards the identification of potential brain structures involved in the TS phenotype. The identified
brain structures may then serve in subsequent molecular genetic and linkage studies. In addition, we regressed cortical thickness
and TS clinical severity scores to assess the relation between TS clinical symptoms and cortical structures. Sixteen sibling
pairs concordant for TS were scanned using a 1.5 T magnetic resonance imaging scanner (age range 10–25, mean 17.19 ± 4.1).
Brain morphology was assessed using the fully automated Civet pipeline at the Montreal Neurological Institute. TS was assessed
using the Children’s Yale-Brown Obsessive Compulsive Scale (CY-BOCS), Yale Global Tic Severity Scale (YGTSS) and the Goetz
Tic Scale. We report high relatedness/similarity estimates for fraternal siblings concordant for TS (r = 0.86–0.60) in the middle frontal-motor/cingulate/insular cortices. Regression analysis revealed significant negative correlations
in the right insula with the YGTSS (r = −0.41, F = 6.09, P < 0.02) and the left cingulated cortex with the (CY-BOCS) (r = −0.35, F = 4.30, P < 0.05). Since previous findings have concluded that normal fraternal siblings are less alike in frontal cortices, the present
findings may be attributed to TS. We speculate that the high ICC between siblings and the negative correlation between TS
symptoms severity and cortical thickness measurements are related to the disturbances in the maturation of the motor–cingulate–insular
cortical neural system that mediate self-regulatory processes. Such delayed maturation may consequently contribute to the
development of TS by releasing motor and vocal tics from regulatory control. These findings may have important genetic implications. 相似文献
8.
The aims of this study were to replicate the results of a previous study (Resnick et al. 1993) and to extend them by examining the evidence for prenatal exposure to androgens versus sibling imitation as a potential
cause of group differences in levels of sensation seeking. Participants were members of the Australian Twin Registry who had
participated in a structured interview study and completed the Zuckerman Sensation-Seeking Scale. Three sets of group comparisons
were conducted: (1) the sensation seeking scores of females from same-sex twin pairs (n = 1,947) were compared to females from opposite-sex twin pairs (n = 564), (2) females from same-sex twin pairs without a brother (n = 580) were compared to same-sex females with a close-in-age older brother (n = 300), and (3) same-sex females who had a close-in-age older brother (n = 300) were compared to females from opposite-sex twin pairs (n = 564). Females from opposite-sex twin pairs obtained significantly higher scores than females from same-sex twin pairs on
the experience-seeking (d = 0.12) and thrill and adventure seeking (d = 0.10) subscales, but not the boredom susceptibility (d = −0.01) or disinhibition (d < 0.01) subscales of the Sensation-Seeking Scale. The modest effects obtained could not be explained by the psychosocial
effect of having a close-in-age brother. Considering these effects alongside the overall sex differences in the Sensation-Seeking
Scales of experience-seeking (d = 0.12 vs. d = 0.18) and thrill and adventure-seeking (d = 0.10 vs. d = 0.83) suggests that prenatal androgens may actually play a large role in the sex difference in the personality trait of
experience seeking, and a smaller role in thrill and adventure-seeking; there was no evidence from this study that prenatal
androgens are important for explaining sex differences in the traits of boredom susceptibility or disinhibition. 相似文献
9.
First, this study examined genetic and environmental sources of variation in performance on a standardised test of academic achievement, the Queensland Core Skills Test (QCST) (Queensland Studies Authority, 2003a). Second, it assessed the genetic correlation among the QCST score and Verbal and Performance IQ measures using the Multidimensional Aptitude Battery (MAB), [Jackson, D. N. (1984) Multidimensional Aptitude Battery manual. Port Huron, MI:Research Psychologist Press, Inc.]. Participants were 256 monozygotic twin pairs and 326 dizygotic twin pairs aged from 15 to 18 years (mean 17 years ± 0.4 [SD]) when achievement tested, and from 15 to 22 years (mean 16 years ± 0.4 [SD]) when IQ tested. Univariate analysis indicated a heritability for the QCST of 0.72. Adjustment to this estimate due to truncate selection (downward adjustment) and positive phenotypic assortative mating (upward adjustment) suggested a heritability of 0.76 The phenotypic (0.81) and genetic (0.91) correlations between the QCST and Verbal IQ (VIQ) were significantly stronger than the phenotypic (0.57) and genetic (0.64) correlations between the QCST and Performance IQ (PIQ). The findings suggest that individual variation in QCST performance is largely due to genetic factors and that common environmental effects may be substantially accounted for by phenotypic assortative mating. Covariance between academic achievement on the QCST and psychometric IQ (particularly VIQ) is to a large extent due to common genetic influences. 相似文献
10.
Jeanne E. Savage Ashlee A. Moore Chelsea K. Sawyers Jessica L. Bourdon Brad Verhulst Dever M. Carney Elizabeth Moroney Laura Machlin Oumaima Kaabi Scott Vrana Christian Grillon Melissa A. Brotman Ellen Leibenluft Daniel S. Pine Roxann Roberson‐Nay John M. Hettema 《Psychophysiology》2019,56(5)
The modulation of the startle response (SR) by threatening stimuli (fear‐potentiated startle; FPS) is a proposed endophenotype for disorders of the fearful‐fearlessness spectrum. FPS has failed to show evidence of heritability, raising concerns. However, metrics used to index FPS—and, importantly, other conditional phenotypes that are dependent on a baseline—may not be suitable for the approaches used in genetic epidemiology studies. Here, we evaluated multiple metrics of FPS in a population‐based sample of preadolescent twins (N = 569 from 320 twin pairs, Mage = 11.4) who completed a fear‐conditioning paradigm with airpuff‐elicited SR on two occasions (~1 month apart). We applied univariate and multivariate biometric modeling to estimate the heritability of FPS using several proposed standardization procedures. This was extended with data simulations to evaluate biases in heritability estimates of FPS (and similar metrics) under various scenarios. Consistent with previous studies, results indicated moderate test‐retest reliability (r = 0.59) and heritability of the overall SR (h2 = 34%) but poor reliability and virtually no unique genetic influences on FPS when considering a raw or standardized differential score that removes baseline SR. Simulations demonstrated that the use of differential scores introduces bias in heritability estimates relative to jointly analyzing baseline SR and FPS in a multivariate model. However, strong dependency of FPS on baseline levels makes unique genetic influences virtually impossible to detect regardless of methodology. These findings indicate that FPS and other conditional phenotypes may not be well suited to serve as endophenotypes unless such codependency can be disentangled. 相似文献
11.
The failure to identify specific non-shared environmental influences on behavior coupled with the belief that shared environmental
factors contribute minimally to individual differences in behavior has led to the concern that major environmental determinants
of behavior may be idiosyncratic, and therefore undetectable. We used data on adoptive (N = 246) and biologically related (N = 130) same-sex sibling pairs (mean ages = 16.1 years older sibling; 13.8 years younger sibling) from the Sibling Interaction
and Behavior Study (SIBS) to determine whether non-idiosyncratic environmental factors shared by siblings contributed to individual
differences in a diverse set of behavioral outcomes. Evidence for shared environmental influence was sought for eight composite
measures covering a wide array of adolescent functioning: Academic Achievement, Total IQ, Substance Use Disorders, Externalizing
Disorders, Internalizing Disorders, Peer Groups, Disinhibited Personality, and Negative Emotionality. For six of eight composites,
significant shared environmental effects, accounting for 14–22% of the variance, were observed for these same-sex sibling
pairs. These findings support the use of adoptive sibling designs to directly estimate shared environmental effects and implicate
the existence of systematic environmental influences on behavior that are potentially detectable.
Edited by Dorret Boomsma and John Hewitt. 相似文献
12.
Rebecca S. Betjemann Erin Phinney Johnson Holly Barnard Richard Boada Christopher M. Filley Pauline A. Filipek Erik G. Willcutt John C. DeFries Bruce F. Pennington 《Behavior genetics》2010,40(2):135-145
Although there has been much interest in the relation between brain size and cognition, few studies have investigated this
relation within a genetic framework and fewer still in non-adult samples. We analyzed the genetic and environmental covariance
between structural MRI data from four brain regions (total brain volume, neocortex, white matter, and prefrontal cortex),
and four cognitive measures (verbal IQ (VIQ), performance IQ (PIQ), reading ability, and processing speed), in a sample of
41 MZ twin pairs and 30 same-sex DZ twin pairs (mean age at cognitive test = 11.4 years; mean age at scan = 15.4 years). Multivariate
Cholesky decompositions were performed with each brain volume measure entered first, followed by the four cognitive measures.
Consistent with previous research, each brain and cognitive measure was found to be significantly heritable. The novel finding
was the significant genetic but not environmental covariance between brain volumes and cognitive measures. Specifically, PIQ
shared significant common genetic variance with all four measures of brain volume (r
g = .58–.82). In contrast, VIQ shared significant genetic influence with neocortex volume only (r
g = .58). Processing speed was significant with total brain volume (r
g = .79), neocortex (r
g = .64), and white matter (r
g = .89), but not prefrontal cortex. The only brain measure to share genetic influence with reading was total brain volume
(r
g = .32), which also shared genetic influences with processing speed. 相似文献
13.
De Moor MH Willemsen G Rebollo-Mesa I Stubbe JH De Geus EJ Boomsma DI 《Behavior genetics》2011,41(2):211-222
Individual differences in adolescent exercise behavior are to a large extent explained by shared environmental factors. The
aim of this study was to explore to what extent this shared environment represents effects of cultural transmission of parents
to their offspring, generation specific environmental effects or assortative mating. Survey data on leisure-time exercise
behavior were available from 3,525 adolescent twins and their siblings (13–18 years) and 3,138 parents from 1,736 families
registered at the Netherlands Twin Registry. Data were also available from 5,471 adult twins, their siblings and spouses similar
in age to the parents. Exercise participation (No/Yes, using a cut-off criterion of 4 metabolic equivalents and 60 min weekly)
was based on questions on type, frequency and duration of exercise. A model to analyze dichotomous data from twins, siblings
and parents including differences in variance decomposition across sex and generation was developed. Data from adult twins
and their spouses were used to investigate the causes of assortative mating (correlation between spouses = 0.41, due to phenotypic
assortment). The heritability of exercise in the adult generation was estimated at 42%. The shared environment for exercise
behavior in adolescents mainly represents generation specific shared environmental influences that seem somewhat more important
in explaining familial clustering in girls than in boys (52 versus 41%). A small effect of vertical cultural transmission
was found for boys only (3%). The remaining familial clustering for exercise behavior was explained by additive genetic factors
(42% in boys and 36% in girls). Future studies on adolescent exercise behavior should focus on identification of the generation
specific environmental factors. 相似文献
14.
Monozygotic (MZ) twin pairs with spouses and children, altogether 787 subjects, completed the Jenkins Activity Survey (JAS). The observed correlations for the various sets of relationships fitted well with biometric models including only parameters for additive genetic effects and, for Type A and Job Involvement, assortative mating. There was no evidence of effects of the family environment (cultural transmission) or genetic dominance (nonadditivity). For all but the Hard Driving and Competitive scale, there was evidence of effects of sex-specific genes. The heritability estimates were, for males and females, respectively, .33 and .39 for Type A, .36 and .48 for Job Involvement, .20 and .52 for Speed and Impatience, and .13 (both sexes) for Hard Driving and Competitive. The estimates given here are deflated by measurement errors and should probably be corrected by multiplying by values in the neighborhood of 1.3. Even after correction, the results suggest that individual differences for Type A and related traits depend more on nonfamilial environment than on genes. 相似文献
15.
Hopkins ND Stratton G Cable NT Tinken TM Graves LE Green DJ 《European journal of applied physiology》2012,112(2):421-427
Flow mediated dilation (FMD) is a surrogate marker of arterial function which can be improved by exercise training. To date,
no study has assessed the magnitude of FMD changes in response to exercise training between groups of mono- (MZ) and di-zygotic
(DZ) twins. The purpose of this study was therefore to compare FMD in MZ- and DZ twins before and after identical exercise
training interventions. At baseline, FMD was assessed using high resolution Duplex ultrasound in 12 twin pairs (6 MZ pairs
13.5 ± 0.8 years, 6 DZ pairs 13.4 ± 0.8 years). Twins completed 8 weeks of exercise training (65–85% HRmax), consisting of three 45-min sessions per week. Change (Δ) scores were entered into twin versus twin intraclass correlation
analyses by group. Change in %body fat (r = 0.63, P = 0.05) was significantly correlated in the MZ, but not the DZ group (r = 0.31, P = 0.23). Change in FMD was also highly correlated in MZ (r = 0.74, P = 0.02) but not in the DZ group (r = 0.37, P = 0.18). Heritability of ΔFMD was estimated at 0.74. Exercise induced changes in FMD were similar within sets of monozygotic
twins but not dizygotic twins. These data suggest that a significant portion of the arterial function response to exercise
training may be genetically determined. 相似文献
16.
Laura A. Baker Susan A. Treloar Chandra A. Reynolds Andrew C. Heath Nicholas G. Martin 《Behavior genetics》1996,26(2):89-102
The relative effects of genetic and environmental factors in producing individual differences in educational achievement are
compared across women and men and over birth cohorts. In a large sample of Australian twin pairs, the heritability of self-reported
educational attainment did not vary among women and men born before and after 1950. In a “psychometric” model of twin resemblance,
based on separate self-reports in 1981 and 1989, genetic factors explained 57% of the stable variance in educational achievement,
while environmental factors shared by twins accounted for 24% of the variance. Corrections for phenotypic assortative mating
for educational level, however, suggested that estimated common-environmental effects could be entirely explained by the correlation
between additive genetic values for mates. Taking this into account, heritability of “true” educational attainment in Australia
may be as high as 82% with the remaining variation being due to individual environments or experiences. Unlike previous studies
in Scandinavian countries, results in Australia suggest that factors influencing educational success are comparable between
women and men and for individuals born at different points during this century. 相似文献
17.
Scores of occupational status, educational attainment, and IQ were obtained for 507 monozygotic and 575 dizygotic male twin pairs born 1931–1935 and 1944–1960. A multivariate genetic analysis with statistics from different cohorts showed heterogeneity between cohorts, and analyses were performed in four separate cohorts. The only set of results which departed clearly from the rest was found for the group born 1931–1935, where the ratio of environmental to genetic effects exceeded those of the other groups. Typical heritability values in the three youngest groups (weighted means) were .43, .51, and .66 for occupation, education, and IQ, respectively. The values in the oldest group were .16, .10, and .37, but this sample is small and the estimates are unstable. Genetic variance influencing educational attainment also contributed approximately onefourth of the genetic variance for occupational status and nearly half the genetic variance for IQ. The values for the between-families variances (reflecting family environment and assortative mating) varied from 2 to 35% in the three youngest groups but were higher for education (62%) and IQ (45%) in the oldest groups. All the between-families variance was common to all three variables. For educational attainment and IQ, the bulk of this between-families variance is probably genetic variance due to assortative mating. The common-factor environmental within-family variances were generally small, and the specific estimates seemed to contain mainly measurement error. 相似文献
18.
K. R. Truett L. J. Eaves E. E. Walters A. C. Heath J. K. Hewitt J. M. Meyer J. Silberg M. C. Neale N. G. Martin K. S. Kendler 《Behavior genetics》1994,24(1):35-49
The Virginia 30,000 comprise 29,698 subjects from the extended kinships of 5670 twin pairs. Over 80 unique correlations between relatives can be derived from these kinships, comprised of monozygotic (MZ) and dizygotic (DZ) twins and their spouses, parents, siblings, and children. This paper describes the first application of a fairly general model for family resemblance to data from the Virginia 30,000. The model assesses the contributions of additive and dominant genetic effects in the presence of vertical cultural inheritance, phenotypic assortative mating, shared twin and sibling environments, and within-family environment. The genetic and environmental effects can be dependent on sex. Assortment and cultural inheritance may be based either on the phenotype as measured or on a latent trait of which the measured phenotype is an unreliable index. The model was applied to church attendance data from this study. The results show that the contributions of genes, vertical cultural inheritance, and genotype-environment covariance are all important, but their contributions are significantly heterogeneous over sexes. Phenotypic assortative mating has a major impact on family resemblance in church attendance. 相似文献
19.
Martina Meszaros Adam Domonkos Tarnoki David Laszlo Tarnoki Daniel Tamas Kovacs Bianka Forgo Jooyeon Lee Joohon Sung Jrgen Vestbo Veronika Müller Laszlo Kunos Andras Bikov 《Journal of sleep research》2020,29(4)
Obstructive sleep apnea is associated with an increased risk of hypertension, diabetes and dyslipidaemia. Both obstructive sleep apnea and its comorbidities are at least partly heritable, suggesting a common genetic background. Our aim was to analyse the heritability of the relationship between obstructive sleep apnea and its comorbidities using a twin study. Forty‐seven monozygotic and 22 dizygotic adult twin pairs recruited from the Hungarian Twin Registry (mean age 51 ± 15 years) attended an overnight diagnostic sleep study. A medical history was taken, blood pressure was measured, and blood samples were taken for fasting glucose, total cholesterol, triglyceride, high‐density lipoprotein cholesterol, low‐density lipoprotein cholesterol and lipoprotein (a). To evaluate the heritability of obstructive sleep apnea and its comorbidities bivariate analysis was performed with an adjustment for age, gender, body mass index (BMI) and smoking after false discovery rate correction and following exclusion of patients on lipid‐lowering and antidiabetic medications. There was a significant correlation between indices of obstructive sleep apnea severity, such as the apnea–hypopnea index, oxygen desaturation index and percentage of sleep time spent with oxygen saturation below 90%, as well as blood pressure, serum triglyceride, lipoprotein (a) and glucose levels (all p < .05). The bivariate analysis revealed a common genetic background for the correlations between serum triglyceride and the oxygen desaturation index (r = .63, p = .03), as well as percentage of sleep time spent with oxygen saturation below 90% (r = .58, p = .03). None of the other correlations were significantly genetically or environmentally determined. This twin study demonstrates that the co‐occurrence of obstructive sleep apnea with hypertriglyceridaemia has a genetic influence and heritable factors play an important role in the pathogenesis of dyslipidaemia in obstructive sleep apnea. 相似文献
20.
In a previous paper (Harden et al. in Behav Gen 37:273–283, 2007) models of genotype–environment interaction were fitted to data from the National Merit Twin Study, resulting in evidence
for an interaction: the heritability of National Merit Qualifying Test scores increased at higher levels of family income.
The present paper investigates two assumptions made in the previous modeling. These were a lack of resemblance between parents
for cognitive skill, and possible correlations between family income and a child’s genes because of the contribution of parental
genes to both. The assumptions were found not to seriously affect estimates of the interaction effect—heritability still increased
with income—but they did make a difference for other parameter estimates from the modeling. One possible explanation of the
observed interaction, decreasing levels of assortative mating at higher income levels, was examined and found not to be consistent
with other evidence from the study. Another possible explanation, a greater freedom of members of DZ pairs at higher income
levels to follow independent interests, remained plausible.
Edited by Irwin Waldman. 相似文献