Intergenerational gains in relative knee height as compared to gains in relative leg length within Taiwanese families

Abstract

Evidence indicates that variation in relative leg length (RLL) is a sensitive indicator of early childhood circumstances, but research presents conflicting evidence of how lower leg growth contributes to variability. This study investigates the extent of intergenerational changes in subischial leg length and knee height relative to stature among father-son, mother-daughter, and midparent-offspring pairs. These changes and differences in the extent of mean change in the two indices within like-sex parent-offspring pairs were assessed using repeated measures ANOVA. Results indicate that within all categories, mean generational differences in both indices were substantial [Delta RLL z: 0.64-0.73; Delta relative knee height (RKH) z: 0.46-0.64] and statistically significant (P < or = 0.010). Mean increases in RLL and RKH across parent-offspring categories were consistently greater in Taipei than Auckland, though only the midparent-offspring generation by location contrast for RLL was statistically significant (P = 0.037). Father-son and mother-daughter average differences were virtually identical for RLL (0.73 z vs. 0.72 z). When differences within pairs in the extent of change in RLL and RKH were assessed directly, mother-daughter mean differences approached significance at an alpha level of 0.05 (Delta = 0.26 z; F = 3.42, df = 1, 42, P = 0.071). Father-son differences were smaller (Delta = 0.09 z) and statistically insignificant suggesting very similar amounts of change in the two indices.