title: [Genetic study on somatotype of child and adolescent twins in Han nationality].
abstract: OBJECTIVE
  To assess the genetic and environmental influences on the somatotype of children and adolescents, and the effects of sex and age.
  
  
  METHODS
  The components of somatotype were calculated by using Heather-Cater method in a total of 376 twin pairs of Han nationality, including 245 monozygotic (MZ) and 131 like-sex dizygotic (DZ) twin pairs aged 6 to 18 years. Model-fitting method by Mx package was performed to evaluate the proportion of variance components and to analyze the effects of sex and age on each component of somatotype using the adjusted data for other two somatotype components. The heritability of each component in different development periods divided by growth spurt was also evaluated.
  
  
  RESULTS
  The estimated heritabilities of endomorphic, mesomorphic and ectomorphic components were 0.45, 0.80, 0.44 in boys, 0.82, 0.79 and 0.81 in girls respectively after adjusting age. In boys, the heritability of endomorphic component during late puberty was significantly higher than that during pre-puberty (t = 4.99, P < 0.01) and puberty (t = 6.16, P < 0.01), while the heritability of ectomorphic component during late puberty was significantly lower than that during pre-puberty (t = 3.35, P < 0.01) and puberty (t = 4.12, P < 0.01). In girls, the heritability of endomorphic (t = 2.77, P < 0.01) or mesomorphic (t = 2.08, P < 0.05) component during pre-puberty was significantly higher than that in early puberty.
  
  
  CONCLUSIONS
  The genetic influence on somatotype of girls should be much more than that of boys, especially on the endomorphic and ectomorphic components. For boys, the mesomorphic component is mainly determined by genetic factors, but the other components are mainly affected by environmental ones. The effects of the development periods on the heritability of somatotype should be paid much attention to.
authors.affiliation: Institute of Child and Adolescent Health, Peking University, Beijing 10083, China.
authors.forename: Yu-Ling
authors.initials: YL
authors.lastname: Li
authors.forename: Cheng-Ye
authors.initials: CY
authors.lastname: Ji
authors.forename: Shun-Hua
authors.initials: SH
authors.lastname: Lu
authors.forename: Li-Ya
authors.initials: LY
authors.lastname: Suo
authors.forename: Tian-Jiao
authors.initials: TJ
authors.lastname: Chen
mesh_terms: D000293:Adolescent; D044466:Asian People; D002648:Child; D002681:China; D005260:Female; D006801:Humans; D008297:Male; D013008:Somatotypes / Q000235:genetics*; D014427:Twins / Q000235:genetics*; D014429:Twins, Dizygotic / Q000235:genetics; D014430:Twins, Monozygotic / Q000235:genetics