中文摘要：

目的 探索不同出生队列BMI遗传度的变化情况。方法 基于中国双生子登记系统丽水和青岛两个时点的双生子，按照出生年份分为1958年及以前出生、1959-1961年出生、1962-1970年出生和1971年及以后出生的4个出生队列，在各个时点分别拟合结构方程，计算不同出生队列在不同年龄的遗传度。结果 每个出生队列中，2012年时的体重、BMI高于2001年；出生于1971年及以后的双生子无论体重和BMI均低于其余出生队列。遗传因素能解释BMI的表型变异为54%-76%；出生于1959-1961年的双生子，BMI的遗传度随年龄上升，其余出生队列遗传度较为稳定。结论 BMI受遗传因素影响较大，出生于1959-1961年的双生子，随着年龄增长，遗传因素对BMI的影响增加。

英文摘要：

Objective To investigate the varying variances of the genetic components in birth cohorts. Methods Twin samples used in the current study were collected from the Chinese National Twin Registry and a two-wave study was conducted, in Qingdao and Lishui regions. Samples were broken down by birth cohort to create four subgroups：-1958, 1959-1961, 1962-1970 and 1970-. Structural equation models were fitted in each subgroup to estimate the genetic and environmental variances. Results From each birth cohort, weight and body mass index in 2012 appeared higher than those in 2001. Twins of 1971-cohort subgroup showed lower weight than in the other cohort subgroups. Except for the 1959-1961 cohort subgroup, the later birth cohorts were inversely related to the body mass indexes. Genetic factors might explain 54%-76% of the total variations on the body mass index. Heritability of body mass index of twins born during 1959-1961 was increasing along with age. Conclusion Genetic factors might explain the main portion which related to the phenotypic variance of body mass index. Effects of genetic factors on body mass index of twins born during 1959-1961 might have increased along with age.