Heritability of somatotype components: a multivariate analysis

Area of Science:

• Human genetics
• Anthropometry
• Twin studies

Background:

• Understanding the genetic and environmental factors influencing human body composition is crucial for public health.
• Heath-Carter somatotype components (endomorphy, mesomorphy, ectomorphy) provide a framework for describing body shape.
• Previous research has primarily focused on adolescent twin studies, necessitating adult data.

Purpose of the Study:

• To investigate the genetic and environmental influences on Heath-Carter somatotype components in adults.
• To determine the heritability and environmental contributions to endomorphy, mesomorphy, and ectomorphy.
• To examine sex differences and covariation among somatotype components.

Main Methods:

• Utilized multivariate path analysis on a dataset of 803 adult Flemish twins (424 pairs).
• Analyzed data from twins aged 18-34 years.
• Applied age-regression to isolate genetic and environmental variances.

Main Results:

• Significant sex differences and covariation were observed among the three somatotype components.
• Additive genetic variance (A), shared environment (C), and unique environment (E) explained population variation.
• Heritability estimates for men: endomorphy (28.0%), mesomorphy (86.3%), ectomorphy (66.5%).
• Heritability estimates for women: endomorphy (32.3%), mesomorphy (82.0%), ectomorphy (70.1%).
• Over 70% of the variation in all components was explained by shared environmental factors, highlighting the importance of multivariate analysis.

Conclusions:

• High heritability for mesomorphy and ectomorphy is maintained into adulthood.
• Endomorphy, reflecting subcutaneous adipose tissue, shows lower heritability in adulthood compared to adolescent studies and BMI.
• The distinct heritabilities of mesomorphy and endomorphy raise questions about using BMI to fully understand the genetics of fatness and obesity.