The familial clustering of age at menarche in extended twin families.

The timing of puberty is complex, possibly involving many genetic factors that may interact with environmental influences. Familial resemblance for age at menarche was studied in a sample of 4,995 female twins, 1,296 sisters, 2,946 mothers and 635 female spouses of male twins. They had indicated their age at menarche as part of a larger longitudinal survey. We assessed assortative mating for age at menarche, gene-environment interaction effects and estimated the heritability of individual differences in pubertal timing. There was significant evidence of gene-environment interaction, accounting... Mehr ...