Gender segregation in childhood.
D005075:Biological Evolution; D002648:Child; D002657:Child Development; D005260:Female; D005783:Gender Identity; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D010379:Peer Group; D010988:Play and Playthings; D002666:Psychology, Child; D012930:Social Dominance; D013694:Temperament