title: Family structure and age at menarche: a children-of-twins approach.
abstract: Girls who grow up in households with an unrelated adult male reach menarche earlier than peers, a finding hypothesized to be an evolutionary strategy for families under stress. The authors tested the alternative hypothesis that nonrandom selection into stepfathering due to shared environmental and/or genetic predispositions creates a spurious relation between stepfathering and early menarche. Using the unique controls for genetic and shared environmental experiences offered by the children-of-twins design, the authors found that cousins discordant for stepfathering did not differ in age of menarche. Moreover, controlling for mother's age of menarche eliminated differences in menarcheal age associated with stepfathering in unrelated girls. These findings strongly suggest selection, and not causation, accounts for the relationship between stepfathering and early menarche.
authors.affiliation: Department of Psychology, University of Virginia, Charlottesville, VA 22902, USA. jm4ky@virginia.edu
authors.forename: Jane
authors.initials: J
authors.lastname: Mendle
authors.forename: Eric
authors.initials: E
authors.lastname: Turkheimer
authors.forename: Brian M
authors.initials: BM
authors.lastname: D'Onofrio
authors.forename: Stacy K
authors.initials: SK
authors.lastname: Lynch
authors.forename: Robert E
authors.initials: RE
authors.lastname: Emery
authors.forename: Wendy S
authors.initials: WS
authors.lastname: Slutske
authors.forename: Nicholas G
authors.initials: NG
authors.lastname: Martin
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D002648:Child; D005190:Family; D005191:Family Characteristics; D005260:Female; D006801:Humans; D007398:Interpersonal Relations; D008297:Male; D008572:Menarche / Q000502:physiology* / Q000523:psychology*; D009034:Mother-Child Relations; D014427:Twins