title: Sex ratios: human twins and fraternal effects.
abstract: Historical data from Finnish populations reveals that, for females, exposure to a male twin in the womb may have significant, life-long, effects on subsequent fitness, with profound implications for the evolution of sex ratios and brood size.
authors: Edward Grey Institute, Department of Zoology, University of Oxford, Oxford OX1 3PS, UK.
authors: Sarah C L
authors: SC
authors: Knowles
authors: Ben C
authors: BC
authors: Sheldon
mesh_terms: D005260:Female; D005298:Fertility; D005387:Finland; D006801:Humans; D008297:Male; D012737:Sex Factors; D012744:Sex Ratio; D014429:Twins, Dizygotic / Q000502:physiology*