Abstract: ObjectiveTo analyze the heritabilities of somatotype components and to examine the genetic and environmental influences on the somatotype among twins aged 3 to 6 years.MethodsThe components of somatotype were calculated by using Heath-Carter method in 72 twin pairs,including 42 monozygotic(MZ)and 30 like-sex dizygotic(DZ) twin pairs aged 3 to 6 years.Heritabilities of somatotype components were estimated by Holzinger formula.ResultsThe results of somatotype dispersion distance(SDD)and somatotype attitudinal distance(SAD)showed that the somatotype of MZ was more similar than that of DZ.The interpair variance of somatotype components showed no significant difference between MZ and DZ.The intrapair variance of mesomorphic and ectomorphic components was greater in DZ than in MZ,but the correlation coefficient was greater in MZ than in DZ.The estimated heritabilities of endomorphic,mesomorphic,and ectomorphic components were 0.38,0.67,and 0.73,respectively.ConclusionThere might be genetic and environmental influence effects on somatotype of children aged 3 to 6 years.The endomorphic component is mainly determined by environmental factors,but mesomorphic and ectomorphic components are mainly affected by genetic ones.