Familial resemblance in somatotype

Area of Science:

• Human Genetics
• Anthropometry
• Behavioral Genetics

Background:

• Understanding the familial aggregation of human physical traits is crucial for distinguishing genetic from environmental influences.
• Somatotype, a measure of body shape, has been hypothesized to have a genetic component, but empirical evidence from family studies is needed.

Purpose of the Study:

• To investigate familial similarities in somatotype components (endomorphy, mesomorphy, ectomorphy) within French Canadian nuclear families.
• To assess the relative contributions of age, gender, energy intake (EI), and physical activity level (AL) to somatotype variation.
• To determine the extent of heritability versus environmental influences on somatotype.

Main Methods:

• Analysis of Health-Carter somatotype components in 938 individuals from 243 nuclear families.
• Calculation of familial correlations (parent-child, sibling, spouse) adjusting for age, gender, and other somatotype components.
• Regression analysis incorporating EI and AL, estimated from 3-day records.

Main Results:

• Age and gender significantly explained variation in somatotype components.
• Energy intake and physical activity level explained additional variance (6-20%) in somatotype components.
• Significant parent-child and sibling correlations (0.14-0.59) indicated familial aggregation, especially for mesomorphy.
• Spouse correlations were non-significant, suggesting assortative mating is not a major factor.

Conclusions:

• Somatotype components exhibit familial aggregation, consistent with genetic transmission across generations.
• Mesomorphy shows the strongest evidence for heritability, followed by endomorphy and ectomorphy.
• While environmental factors (EI, AL) contribute to somatotype, familial resemblance is largely independent of these measured variables.