title: Genetic analysis of twins' naturalistically observed behavior.
mesh_terms: D002668:Child Rearing; D002675:Child, Preschool; D003858:Dependency, Psychological; D005260:Female; D005824:Genetics, Behavioral; D006801:Humans; D007804:Language Development; D008297:Male; D008425:Maternal Behavior; D009043:Motor Activity; D010287:Parent-Child Relations; D011247:Pregnancy; D012919:Social Behavior; D014427:Twins; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic