Familial concordance for height and its components: analyses from the Breakthrough Generations Study.

Objectives: To assess familial resemblance for height, arm span, and components of these, and differences between concordance for short and tall heights.

Methods: We examined whether female relatives were similar for six anthropometric measurements (height, arm span, leg, trunk and arm length, and leg:trunk length ratio). Subjects were 31,622 related individuals aged 16-102 yr participating in the UK Breakthrough Generations Study. Height and arm span were self-reported, limb and trunk length were measured in a subset (N = 508) by study investigators, and paternal height was reported by the daughter. Data were analyzed using correlations and Poisson regression.

Results: Correlation coefficients within families were 0.4 for height, 0.3 for arm span, and 0.5 for leg length, trunk length, leg:trunk ratio, and arm length. Women had a relative risk (RR) of being short (i.e., in the lowest height quintile) of 2.3 (95% confidence interval [CI] = 2.1-2.5) if their mother was short, 2.1 (95% CI = 1.9-2.3) if their father was short, and 3.7 (95% CI = 3.4-4.0) if both parents were short. RRs of being tall (i.e., in the highest height quintile) were 2.3 (95% CI = 2.1-2.5), 2.4 (95% CI = 2.2-2.6), and 4.4 (95% CI = 4.1-4.8) if their mother, father or both were tall, respectively.

Conclusions: We have shown, for the first time, that leg:trunk length ratio and arm length aggregate within families. Concordance seemed to be stronger for tall than short heights.