The magnitude of changes in linear growth within Taiwanese families: intrinsic sex-associated biology, socially mediated behaviors, or both?

ABSTRACT

OBJECTIVE: This study evaluates competing hypotheses about implications of greater female growth canalization for differences in male and female growth as developmental settings improve. PARTICIPANTS AND METHODS: Intergenerational declines in gender bias and rapid economic growth in Taiwan permit assessment of the two hypotheses using anthropometric and background information from 107 Taiwanese parents and their young adult offspring. Differences in parents' values were first evaluated across grandfathers' occupational status categories reflecting good to relatively poor early circumstances in the parental generation. The extent of intergenerational change in heights or knee heights within 56 father-son pairs were then compared with those in 51 statistically independent mother-daughter pairs across the same occupational categories using repeated measures analyses. RESULTS: Change in mean heights and knee heights across grandfathers' occupational categories were noticeably greater for fathers than mothers. Overall, intergenerational gains within families in height and knee height were statistically significant (p < 0.0005) in father-son (3.89 cm; 1.85 cm) and mother-daughter pairs (4.14 cm; 1.67 cm). However, among families where grandfather's occupations were "privileged," father-son pairs are similar in average height (Δ = -0.36 cm) and knee height (Δ = 0.53 cm) while mothers were significantly shorter (Δ = 3.88 cm) with shorter knee heights (Δ = 1.74 cm) than their daughters. DISCUSSION: The hypothesis that females are inherently less capable of responding to growth promoting characteristics of early environments is not supported. Intergenerational declines in male preference combined with rapid but equitable economic growth better account for intergenerational changes reported.