title: The effect of paternal age on offspring intelligence and personality when controlling for paternal trait level.
abstract: Paternal age at conception has been found to predict the number of new genetic mutations. We examined the effect of father's age at birth on offspring intelligence, head circumference and personality traits. Using the Minnesota Twin Family Study sample we tested paternal age effects while controlling for parents' trait levels measured with the same precision as offspring's. From evolutionary genetic considerations we predicted a negative effect of paternal age on offspring intelligence, but not on other traits. Controlling for parental intelligence (IQ) had the effect of turning an initially positive association non-significantly negative. We found paternal age effects on offspring IQ and Multidimensional Personality Questionnaire Absorption, but they were not robustly significant, nor replicable with additional covariates. No other noteworthy effects were found. Parents' intelligence and personality correlated with their ages at twin birth, which may have obscured a small negative effect of advanced paternal age (<1% of variance explained) on intelligence. We discuss future avenues for studies of paternal age effects and suggest that stronger research designs are needed to rule out confounding factors involving birth order and the Flynn effect.
authors.affiliation: Institute of Psychology, Humboldt University of Berlin, Berlin, Germany ; Institute of Psychology, Georg August University Göttingen, Göttingen, Germany.
authors.forename: Ruben C
authors.initials: RC
authors.lastname: Arslan
authors.affiliation: Institute of Psychology, Georg August University Göttingen, Göttingen, Germany.
authors.forename: Lars
authors.initials: L
authors.lastname: Penke
authors.affiliation: Department of Psychology and Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, Edinburgh, United Kingdom.
authors.forename: Wendy
authors.initials: W
authors.lastname: Johnson
authors.affiliation: Department of Psychology, University of Minnesota, Minneapolis, Minnesota, United States of America.
authors.forename: William G
authors.initials: WG
authors.lastname: Iacono
authors.affiliation: Department of Psychology, University of Minnesota, Minneapolis, Minnesota, United States of America.
authors.forename: Matt
authors.initials: M
authors.lastname: McGue
mesh_terms: D000293:Adolescent; D000328:Adult; D005260:Female; D006801:Humans; D007360:Intelligence / Q000235:genetics; D008297:Male; D008423:Maternal Age; D008875:Middle Aged; D015233:Models, Statistical; D009154:Mutation; D010331:Paternal Age; D010551:Personality / Q000235:genetics; D055815:Young Adult