Parental height: childhood environment and subsequent adult height in a national birth cohort.

Low parental social class was associated with shorter adult stature in offspring in a national birth cohort. Since short adult stature is a risk factor for serious illness, particularly heart disease, origins of the observed class differences were sought in the childhood environment and in combined genetic and environmental factors represented by midparent height and birthweight. In addition to social class the childhood environmental factors of birth order, number of surviving younger siblings, overcrowding and mother's education were found to be significant and independent predictors of adult height, even after adjusting for parental heights and birthweight, and had therefore a long-term intragenerational effect. Both midparent height and birthweight constitute a combination of environmental and genetic influences, and therefore to some extent are an intergenerational effect. Improvements in environmental factors are thus likely to reduce social variation in adult height for both intra and intergenerational reasons.