title: Genetic and environmental factors in relative weight from birth to age 18: the Swedish young male twins study.
abstract: OBJECTIVE
  To investigate the contributions of genetic and environmental factors to the development of relative weight during the growth period.
  
  
  METHODS
  Longitudinal twin study.
  
  
  METHODS
  Two-hundred and thirty-one monozygotic and 144 dizygotic complete male twin pairs born between 1973 and 1979 were measured annually from birth to 18 years of age.
  
  
  RESULTS
  Body mass index (BMI, kg/m(2)) at age 18 correlated with BMI at age 1 (r=0.32, 95% confidence intervals (CI) 0.21-0.42), and this correlation increased steadily up to age 17 (r=0.91, 95% CI 0.89-0.93). Major part (81-95%) of these trait correlations was attributable to correlate additive genetic factors, but also unique environmental correlations were present during the whole-growth period. The correlation between ponderal index (kg/m(3)) at birth and BMI at age 18 was small (r=0.09, 95% CI 0.02-0.15) and totally because of correlated unique environmental factors.
  
  
  CONCLUSIONS
  Our results suggest persistent genetic regulation of BMI from age 1 to 18. However, environmental factors, not shared by siblings, also affected the correlations of BMI. A small specific environmental correlation was found between ponderal index at birth and BMI at age 18, which may reflect the effect of neonatal environmental factors on adult BMI. A challenge to the future research is to identify chromosome regions and specific genes regulating the development of BMI as well as environmental factors affecting BMI through the growth period independently or interacting with genetic factors.
authors: Department of Public Health, University of Helsinki, Helsinki, Finland.
authors: K
authors: K
authors: Silventoinen
authors: K H
authors: KH
authors: Pietiläinen
authors: P
authors: P
authors: Tynelius
authors: T I A
authors: TI
authors: Sørensen
authors: J
authors: J
authors: Kaprio
authors: F
authors: F
authors: Rasmussen
mesh_terms: D000293:Adolescent; D041923:Adolescent Development / Q000502:physiology*; D001724:Birth Weight / Q000502:physiology; D001827:Body Height / Q000502:physiology; D015992:Body Mass Index; D049628:Body Size / Q000502:physiology; D001835:Body Weight / Q000235:genetics*; D002648:Child; D002657:Child Development / Q000502:physiology*; D002675:Child, Preschool; D004777:Environment; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008137:Longitudinal Studies; D008297:Male; D008957:Models, Genetic; D013548:Sweden / Q000453:epidemiology; D014427:Twins / Q000235:genetics*; D014429:Twins, Dizygotic / Q000235:genetics; D014430:Twins, Monozygotic / Q000235:genetics