The NHLBI twin study of cardiovascular disease risk factors: methodology and summary of results

Coronary heart disease (CHD) risk factors were studied in 250 monozygotic (MZ) and 264 dizygotic (DZ) male veteran twin pairs, aged 42-56. All coronary heart disease risk factors studied showed significant correlations in both MZ and DZ twins. Substantial genetic variation was detected for height, blood pressure, glucose intolerance, uric acid, plasma triglyceride, and relative weight but little or no significant genetic variability in low density lipoprotein cholesterol (LDL), high density lipoprotein cholesterol (HDL), total plasma cholesterol or hematocrit was demonstrable. These findings suggest that familial aggregation results from genetic influence on blood pressure, glucose intolerance, uric acid, triglyceride and, possibly, obesity, while largely shared environmental factors contribute to familial similarities in HDL, LDL, total cholesterol and hematocrit.     

Plasma cholesterol variation in the National Heart, Lung and Blood Institute Twin Study

Plasma cholesterol was measured in the fifth decade of the life of 249 pairs of monozygotic (MZ) and 262 pairs of dizygotic (DZ) World War II veteran twins and 70% of the same cohort 10 years later. There were no significant differences between the mean cholesterol values for MZ and DZ twins, and the within DZ pair mean squares were significantly larger than the within MZ pair mean squares for all of the cholesterol variables measured. However, the DZ twins were found to have greater total variance, positive skewness, and leptokurtosis than the MZ twins for total and high-density lipoprotein cholesterol, and the total/high-density ratio. Comparisons with published data revealed that the variance of DZ twins was similar to that of singletons while the MZ twins have smaller total variance, perhaps owing to a missing component of variation. Hypotheses for the source of the differences in the zygosity distributions are proposed including environmental influences (pre- or post-natal and within- or among-families), genetic differences, and selection at the time of induction into the armed services. Because of the differences in total variance of the two zygosities it is difficult to know which estimates of genetic variance or heritability have the least bias. However, these data provide clues that may lead to further understanding of sources of plasma cholesterol variation that could be important to the future understanding of risk for coronary heart disease.     

Lifestyle factors in monozygotic and dizygotic twins

In examining genetic influences on biological variables using twins, it may be important to examine the distribution between and within twin pairs of demographic and lifestyle factors that may themselves affect the biological variable being studied. We explored the distribution of demographic and lifestyle factors that may affect blood lipid levels or ischaemic heart disease (IHD) risk among a sample of 106 monozygotic (MZ) and 94 like-sex dizygotic (DZ) twin pairs. In our sample, MZ twins were statistically significantly different from DZ twins only in marital status, cigarette smoking habits, and the ratio of polyunsaturated to saturated fat (P:S ratio) in their dietary intake. The latter variable was among many dietary variables examined (using 4-day weighed food diaries), and the size of the difference in intake was small. When comparisons were made of the similarities within twin pairs, we found members of MZ twin pairs to be statistically significantly closer than DZ twins in educational achievement, occupation, cigarette smoking, and exercise habits, and the number of days a week on which alcohol was consumed. These last three variables were consistently closer among twins with closer contact than among those with a smaller degree of current shared environment. For 12 of the 13 nutrients examined, the within-pair correlations were higher for MZ than for DZ twins, although our test for significant genetic variance showed statistical significance only for intake of complex carbohydrates. We conclude that MZ twins share demographic and lifestyle factors that might influence the risk of IHD and blood lipid levels to a greater degree than do DZ twins, although it is difficult to say if these similarities in lifestyle result from genetic influences or not. Nevertheless, ascribing differences between correlations in MZ and DZ twin pairs for lipid levels as being purely "genetic"--as implicit in conventional measures of heritability--is likely to overestimate the influence of genetic factors.     

Heritability of body mass index in pre-adolescence, young adulthood and late adulthood

Increased body mass index (BMI) is a worldwide health issue. Individual differences in the susceptibility to increased BMI could be related to genes or environment. We performed a systematic review of genetic studies on BMI in pre-adolescence, young adulthood and late adulthood. We searched PubMed and EMBASE with heritability, body mass index, BMI, weight, height, anthropometry and twins as search terms. Studies reporting intra-pair correlations of healthy twin pairs that were raised together were included. This resulted in the inclusion of 8,179 monozygotic (MZ) and 9,977 dizygotic (DZ) twin pairs from twelve published studies in addition to individual participant data for 629 MZ and 594 DZ pairs from four twin registries. Structural equation modelling with intra-pair twin correlations showed that the heritability of BMI remained high over all age categories ranging from 61% (95% CI 54-64%) to 80% (95% CI 76-81%) for male and female subjects combined, while unique environmental influences increased from 14% (95% CI 13-15%) to 40% (95% CI 37-43%) with increasing age. Heritability of BMI remains consistently high over different age categories. Environmental changes over time do not seem to have as big a relative impact on an individual's weight as previously reported, suggesting a mainly genetic influence on variation in BMI over the years.     

儿童青少年双生子瘦素遗传度估计及影响因素分析

目的 分析影响儿童青少年瘦素的遗传因素和环境因素,探讨性别、年龄和体质量指数(BMI)的作用,为儿童肥胖早期预防提供依据.方法 选择6～18岁同性别双生子337对,平均年龄(12.3±3.5)岁,其中同卵双生子257对,异卵双生子80对.采用DNA微卫星多态性鉴定卵性.应用Mx结构方程模型分别计算年龄和BMI调整前后瘦素的遗传度,并检验性别、年龄和BMI对于模型的作用.结果 不同性别间身高、体重和瘦素水平差异均有统计学意义(P值均＜0.05).相关分析显示,瘦素水平与性别、年龄和BMI相关(P值均＜0.0l).遗传分析发现,调整前年龄方差在女生中影响较大,而男生则受共同环境方差影响较大.调整后男生特异性性别方差降低,最适模型为ACE(scale)模型.男、女生瘦素遗传模型一致,遗传度为20％.结论 儿童青少年人群中瘦素水平与性别、年龄和BMI相关.瘦素受遗传和环境因素共同影响.调整年龄及BMI后,瘦素遗传度不受性别影响.     

双生子艾森克人格与血液生化指标的相关性研究

[目的 ]了解双生子艾森克人格特点及遗传因素对艾森克人格的影响 ,探讨血液生化指标与艾森克人格的相关性。 [方法 ] 2 0 0 1年 12月对青岛市 89对 2 4岁以上的双生子 (同卵 5 5对 ,异卵 3 4对 )进行艾森克人格测试 ,检测 3 7项血液生化指标 ,并进行相关分析。 [结果 ]同卵双胞胎之间在N(情绪稳定性 )因子的相关系数高于异卵双胞胎 ,N因子的遗传度为 0 45。人格因素中只有N因子与几项生化指标有相关关系 (r <0 3 0 )。 [结论 ]艾森克人格因素中的N因子受遗传作用的倾向较大 ,血液生化指标水平并不决定人的个性心理特征。     

Clustering of high density lipoprotein cholesterol levels in premenopausal and postmenopausal female twins

Previous family and twin studies indicate that genetic variation makes an important contribution to individual variation in high density lipoprotein cholesterol (HDL) levels, even after adjustment for covariates (such as obesity and alcohol consumption) that also cluster in families. However, most studies assume that genetic mechanisms affecting variation in HDL level are the same in all subgroups of the population (e.g., men versus women, by age). Using data from the Kaiser-Permanente Women Twins Study, we found different patterns of clustering for monozygotic (MZ) and dizygotic (DZ) twins depending on menopausal status. Premenopausal MZ twins were more similar than postmenopausal MZ twins (r_i = 0.79 and r_i = 0.61, respectively, after adjustment for age, alcohol consumption, smoking status, degree of obesity, and leisure-time exercise); premenopausal and postmenopausal DZ twins were alike to the same extent (r_i = 0.31 and r_i = 0.32, respectively, adjusted as above). These data suggest that either postmenopausal MZ twins have a greater degree of shared environment than postmenopausal DZ twins (e.g., postmenopausal female hormone use) or that genetic mechanisms that affect individual variation in HDL level differ in pre- and postmenopausal women. Data were not available on postmenopausal female hormone use. If genetic mechanisms that influence variation in HDL levels differ between pre- and postmenopausal women, genetic epidemiologic methods that assume that genetic and environmental sources of variation are the same for all groups of individuals may lead to false conclusions. © 1993 Wiley-Liss, Inc.     

Heritability of body size and muscle strength in young adulthood: a study of one million Swedish men

Moderate heritability for skeletal muscle strength has been reported in twin studies, but genetic co-variation between muscle strength at different parts of body and body size is not well known. Further, representativeness of twin cohorts needs to be critically evaluated. Height, weight, elbow flexion, hand grip and knee extension strength were measured in young adulthood in 1,139,963 Swedish men born between 1951 and 1976. We identified 154,970 full-brother pairs and 1582 monozygotic (MZ) and 1864 same-sex dizygotic (DZ) complete twin pairs. The data were analyzed using quantitative genetic modeling for twin and family data. Twins compared to singletons and MZ twins compared to DZ twins were shorter, lighter and had lower muscle strength. In singletons, there was more variation in weight and the strength measures compared to twins with known zygosity but not when compared to twins with unknown zygosity. Full-sib correlations for these traits were lower than DZ correlations. Additive genetic factors explained 81% of variation in height, 59% in body mass index and 50-60% in the strength measures. Additive genetic correlations varied from 0.13 between height and elbow flexion strength to 0.78 between elbow flexion and hand grip strength. Our results suggest that extra variation may exist in general populations not found in twin samples, probably because of selection due to non-participation. This may have inflated heritability estimates in previous twin studies. Nonetheless, we showed that genetic factors affect muscle strength and part of these genes are common to different strength indicators and body size.     

Risk factors for coronary heart disease in adult female twins. Genetic heritability and shared environmental influences

The contributions of shared genes and shared environments to familial aggregation of coronary heart disease risk factors were investigated by genetic and epidemiologic analysis of 434 adult female twin pairs from the Kaiser-Permanente Twin Registry in Oakland, California, during 1978 and 1979. Initial estimates of genetic heritability were statistically significant for serum levels of high density lipoprotein (HDL) cholesterol, low density lipoprotein (LDL) cholesterol, triglycerides, and Quetelet index, but were only marginally significant for systolic and diastolic blood pressures. These estimates were biased, however, because sisters in the same identical twin pair were more similar than sisters in the same fraternal twin pair not only with respect to shared genes but also with respect to shared environmental and behavioral influences. Heritability was estimated again after adjusting for shared environmental and behavioral effects by multiple regression analysis. Genetic heritability remained significant for HDL cholesterol (0.66), LDL cholesterol (0.88), triglycerides (0.53), and relative weight (0.55) but not for systolic (0.42) and diastolic (0.25) blood pressures. The strong genetic components of the levels of LDL cholesterol, HDL cholesterol, and relative weight may in part explain why some women have high levels of these coronary disease risk factors despite following recommended health behaviors.     

The heritability of cause-specific mortality: a correlated gamma-frailty model applied to mortality due to respiratory diseases in Danish twins born 1870-1930

The genetic influence on susceptibility to diseases of the respiratory system and all-cause mortality was studied using data for identical (MZ) and fraternal (DZ) twins. Data from the Danish Twin Register include 1344 MZ and 2411 DZ male twin pairs and 1470 MZ and 2730 DZ female twin pairs born between 1870 and 1930, where both individuals were alive on 1 011943. We used the correlated gamma-frailty model. Proportions of variance in frailty attributable to genetic and environmental factors were assessed using the structural equation model approach. For all-cause mortality the correlation coefficients of frailty for MZ twins tend to be higher than for DZ twins. For mortality with respect to respiratory diseases this effect was only seen in females, whereas males showed the opposite effect. Five standard biometric models are fitted to the data to evaluate the magnitude and nature of genetic and environmental factors on mortality. Using the best fitting biometric model heritability for cause of death was found to be 0.58 (0.07) for all-cause mortality (AE-model) and zero for diseases of the respiratory system for males. Heritability was 0.63 (0.11) for all-cause mortality (DE-model) and 0.18 (0.09) for diseases of the respiratory system (DE-model) for females. The analysis confirms the presence of a strong genetic influence on individual frailty associated with all-cause mortality. For respiratory diseases, no genetic influence was found in males and only weak genetic influence in females. The nature of genetic influences on frailty with respect to all-cause mortality is probably additive in males and dominant in females, whereas for frailty with respect to deaths caused by respiratory diseases in females, there are genetic factors present which are caused by dominance. Environmental influences are non-shared with exception of frailty with respect to respiratory diseases in males, where the shared environment plays an important role.     

Lifestyle and blood pressure levels in male twins in Utah

Healthy male monozygotic (MZ) and dizygotic (DZ) twin pairs (MZ pairs = 77; DZ pairs = 88) were studied to assess the effect of dietary intake, physical activity, physical fitness, body mass index (BMI), sum of the triceps and subscapular skinfold measurements, alcohol and caffeine consumption, and smoking patterns on blood pressure. Data on physical activity, detailed dietary intake, medical history, and demographics were obtained from a questionnaire. A bicycle ergometer was used to estimate level of fitness; other medical information was ascertained from physical examination. After normalizing the study variables, intraclass correlations for BMI and the sum of the triceps and subscapular skinfold measurements were higher in MZ than in DZ twin pairs (BMI: MZ r = 0.76, DZ r = 0.48; skinfolds: MZ r = 0.73, DZ r = 0.28), as were VO2max(MZ r = 0.63, DZ r = 0.25) and post-bike heart rate (MZ r = 0.69, DZ r = 0.19). Both systolic (SBP) and diastolic blood pressure (DBP) had high heritability estimates (SBP = 0.60, and DBP = 0.66). Using factor analysis, four major lifestyle factors were identified and categorized as: 1) dietary intake; 2) a factor heavily weighted by cigarette smoking, alcohol and caffeine consumption; 3) fatness; 4) physical activity and physical fitness. Adjustment for these factors did not alter heritability estimates for either SBP or DBP.     

遗传与环境因素对女性青春期性征发育的影响

目的探讨遗传与环境因素对女性青春期性征发育的影响,为进一步深入研究女性青春期发育提供依据。方法以学校登记为基础,募集6~18岁女性双生子180对,其中单卵双生(MZ)132对,二卵双生(DZ)48对,按Tanner标准进行青春发育分期,询问有无月经初潮及月经初潮年龄。结果乳房开始发育的年龄为9~12岁,阴毛开始发育的年龄集中在9~13岁,月经初潮年龄多集中在11~13岁。月经初潮、性征发育一致率均为MZ>DZ,月经初潮的遗传指数为0.71,乳房和阴毛发育的遗传指数分别为0.34,0.45。月经初潮年龄的组内相关系数MZ>DZ(P<0.001),偶内均方MZ相似文献   

Monozygotic co-twin analyses of body composition measurements and serum lipids

OBJECTIVE: To evaluate BMI and direct measures of body fat (BF) and lean body mass (LBM) in relation to fasting serum lipid profiles in a large Chinese population based twin sample using a monozygotic (MZ) co-twin analysis. METHODS: Adiposity measures collected 1998-2000 on 987 MZ female 20-60 year old twin pairs (n=1974) included BMI, waist circumference (WC), waist/hip ratio (WHR), LBM, trunk fat (TF), %TF, total BF, and % total BF (measured by DEXA). Serum lipids included total cholesterol (TC), triglycerides (TG), LDL, and HDL. Co-twin analyses and conventional regression analyses were used to assess the association between individual adiposity and LBM measures, and serum lipids. RESULTS: In this lean population with a mean BMI 21.8 (2.8), we observed considerable variability in adiposity measures and serum lipids. A positive linear association between all adiposity measures with LDL, TC, and TG, and a negative linear association with HDL was observed. A 1-unit z-score increase of adiposity measures, reflecting fat distribution, was associated with increases in (mmol/L) TC (0.063 to 0.164), LDL (0.064 to 0.131), TG (0.049 to 0.164), and a decrease in HDL (0.021 to 0.038) while controlling for matched factors within twin pairs (i.e., age and unmeasured confounders). However, similar associations were not observed for LBM. CONCLUSION: It is the BF (not LBM) that appears to be associated with serum lipid profiles. This study underscores that in populations where BMI is highly correlated with BF, BMI can be used as a surrogate for BF in evaluating risk of dyslipidemia. Otherwise, direct measures of BF are needed.     

Socioeconomic position and twins' health: a life-course analysis of 1266 pairs of middle-aged Danish twins

BACKGROUND: The association between socioeconomic circumstances and health in adulthood could come about through processes that may be divided into factors experienced early in life and those experienced in later adulthood. In order to disentangle the influences on health of the early genetic, prenatal and rearing environmental factors from environmental factor later in life, we compared the health status among male and female twin pairs who lived together during childhood and were discordant or concordant on adult socioeconomic position. METHODS: A cross-sectional survey among a random sample of middle-aged Danish twins was conducted in 1998-99. The study population included 1266 like-sex twin pairs [52.5% monozygotic (MZ) and 47.6% dizygotic (DZ)]. Data were obtained on childhood and adult social class and on height, BMI, grip strength, depression symptoms, self-rated health, cognitive function, physical activity, smoking, alcohol and food intake. RESULTS: The expected associations between the individual twins' adult social class and health measures were observed. Among DZ male twins discordant on adult social class, the higher social class twin was on average significantly taller and had higher cognitive test scores. Among DZ female twins discordant on adult social class, the higher social class female twin was more physically active and had a higher cognitive test score. There were no significant health disparities or behavioural differences between the members of MZ twin pairs discordant on adult social class. For most health outcomes, the variability within twin pairs was related to zygosity (higher for DZ than for MZ) but not to social class. CONCLUSION: This study suggests that the relationship between adult social class and health outcomes in Denmark is due mainly to selection effects rather than a causal effect of social class exposures on health and behaviour.     

双生子儿童贫血状况分析

目的通过分析双生子儿童贫血状况和贫血同病率,探讨其遗传和环境效应.方法选取5～19岁双生子228对,其中MZ(单卵双生子)142对,DZ(二卵双生子)86对,在DNA卵性鉴定基础上,以成对法计算同病一致率、调整BMI前后组内相关系数及遗传度.结果双生子儿童贫血检出率与一般人群无明显差异,贫血同病一致率分别为MZ 0.28,DZ 0.15,Hb(血红蛋白)遗传度为0.23.调整BMI前后MZ与DZ组内相关系数和遗传度无显著变化.结论儿童贫血状态受遗传及环境因素共同影响,环境效应更明显.     

中国成年双生子体质指数的分布特征

目的 描述中国双生子登记系统（CNTR）成年双生子BMI的分布特征,探索BMI在双生子人群中的特殊分布规律,为超重及肥胖高危因素分析和制定防制策略提供线索和基础资料。方法 选自CNTR中2010-2018年完成问卷调查的双生子对,纳入≥ 18岁具有完整双生子对登记信息,且身高、体重等关键变量无缺失或异常者进行分析,共计32 725对成年双生子。描述CNTR项目成年双生子BMI的人群、地区分布特征及双生子对内成员BMI差异的分布现况。结果 研究对象年龄（34.6±12.4）岁,同性别双生子对79.7%。研究对象平均BMI为22.5 kg/m²,超重率为23.7%,肥胖率为4.9%。男性、50~59岁组、北方地区、低文化程度者、在婚者的双生子超重率和肥胖率相对更高（P<0.001）。同卵和异卵间差异无统计学意义,但先出生的双生子超重和肥胖率略高于后出生者（P<0.05）。同性别双生子对内分析发现,对内BMI差异与年龄呈正相关（趋势性检验P<0.001）,异卵差异高于同卵,且卵型间差异随年龄增长发生变化。BMI一致率存在卵型差异（P<0.05）,同卵高于异卵。结论 本研究的双生子人群BMI的分布存在人群和地区差异;BMI为可遗传的性状,且遗传作用可能随年龄而变化。     

双生子A型人格与高血压及血生化指标研究

目的 了解双生子A型人格与高血压及血液生化指标的关系。方法 利用遗传流行病学方法对青岛市89对24岁以上双生子(同卵55对，异卵34对)进行调查。并进行A型人格测试，以比较同卵与异卵双生于A型人格得分的相关程度、A型人格及血压的一致性。推测遗传与环境因素对A型人格的影响，A型人格与高血压的关系，并探讨血液生化指标与A型人格的关系。结果 经KAPPA一致性检验，同卵(MZ)双生子之间A型人格存在着显的一致性(P＜0．001)，而异卵(DZ)双生子之间的一致性无显性差异(P＝0．802)。同时，MZ双生子之间A型人格和血压也存在显的一致性(P＜0．001)，而DZ双生子之间A型人格和血压无明显一致性(P＝0．102)。有A型人格的双生子血压的收缩压明显高于非A型人格的双生子(P＜0．05)。许多生化指标与A型人格因素相关，但是所计算出的相关系数大都小于0．30，属于弱相关。结论 MZ双生子A型人格及高血压之间存在着显的一致性，而这种一致性在DZ双生子表现不明显。A型人格是高血压的危险因素之一。A型人格与所研究血液基本生化指标之间相关较弱。     

Sex-specific effects for body mass index in the new Norwegian twin panel

Sex-specific effects for body mass index (BMI) were explored in a newly established, population-based Norwegian twin panel. The sample includes 5,864 individuals, aged 18–25 years, who responded to a questionnaire containing items for zygosity classification, height, weight, health, health-related behaviors, well-being, and demographic information. Among the 2,570 intact pairs who returned the questionnaire there were 416 identical (MZ) male pairs, 387 fraternal (DZ) male pairs, 528 MZ female pairs, 443 DZ female pairs, and 796 unlike-sexed pairs. Alternate sets of models testing for either sex-specific genetic or environmental parameters were evaluated using structural equation analysis. Results from the most parsimonious model indicated that the genes contributing to variation in BMI are not identical for men and women; rather, some genetic effects were shared by the sexes and some were unique to each sex. Total variation in BMI could be explained by sex-specific additive genetic effects, as well as genetic and non-shared environmental effects common to men and women. Estimates of heritability were .708 for men and .789 for women, and the male-female genetic correlation was 0.622. The series of models specifying sex-specific shared environment also fit the data and suggests that shared environmental factors may be important for males but not for females. The findings raise questions concerning the relationship between sex-specific effects for BMI and sex differences in health outcomes. ©1995 Wiley-Liss, Inc.     

双生子的血清脂质和脂蛋白遗传度及影响因素分析

目的　分析儿童、青少年的血脂指标遗传度及影响因素。方法　选择 5～ 19岁双生子2 36对 ,平均年龄 (11 2± 3 4 )岁 ,其中同卵双生子 14 3对 ,异卵双生子 93对。在DNA卵性鉴定基础上 ,以组内相关系数法及Falconer公式计算调整年龄性别前后的遗传度 ,偏态数据进行对数转换 ;校正年龄性别 ,分析相关体格、生化指标对血脂的影响。结果　同卵与异卵双生子间甘油三酯对内方差及相关系数的差异均无显著性 ;总胆固醇、高密度脂蛋白胆固醇 (HDL C)、低密度脂蛋白胆固醇 (LDL C)和脂蛋白 (a)对内方差及相关系数的差异有显著性 ,遗传度估计值分别为 0 5 6、0 5 5、0 4 9和 0 5 8,调整年龄性别后各指标估计遗传度分别为 0 6 3、0 6 3、0 5 5和 0 6 4。总胆固醇、HDL C、LDL C和脂蛋白(a)与年龄呈负相关 ;女孩的总胆固醇、HDL C、LDL C稍高于男孩。校正年龄性别后除脂蛋白 (a)外各血脂指标多数与体重指数、体脂率及培利迪西指数相关 ,与血压、血糖和血钙等也有相关性。结论　总胆固醇、HDL C、LDL C和脂蛋白 (a)受遗传因素影响较大 ,而甘油三酯主要受环境因素影响。儿童的血脂水平受年龄和性别的影响 ,与反映体脂和机体营养发育的指标相关。     

双生子学龄儿童体格发育遗传学分析

目的 分析遗传与环境因素对学龄双生子儿童体格发育的影响,分析其中年龄和性别的作用.方法测量297对6～12岁(同卵167对,同性别异卵90对,异性别异卵40对)学龄儿童身高、坐高、体重、胸围、肱三头肌皮褶、肩胛下皮褶、髂前皮褶厚度;用Mx软件拟合最佳结构方程模型.结果各体格指标均与年龄相关,仅肱三头肌皮褶厚度与性别相关;各指标的遗传模型均为ACES,遗传方差组分高于环境方差组分,男性皮褶厚度的共同环境效应高于女性,皮褶厚度的年龄方差(0.02 ～0.17)明显低于其他指标(0.35 ～0.74);校正年龄后,遗传度分别为身高(男0.80,女0.83)、坐高(男0.76,女0.79)、体重(男0.53,女0.73)、胸围(男0.72,女0.66)、肱三头肌皮褶(男0.51,女0.87)、肩胛下皮褶(男0.56,女0.86)、髂前皮褶(男0.51,女0.83),女生体重及皮褶厚度的遗传度均明显高于男生.结论遗传因素对学龄儿童体格发育起主要作用,但年龄、性别对其也有一定影响.