Emergence and persistence of behavioral differences in twins.
D000367:Age Factors; D001288:Attention; D002648:Child; D002652:Child Behavior; D002657:Child Development; D002675:Child, Preschool; D003448:Crying; D004644:Emotions; D005149:Facial Expression; D005260:Female; D005824:Genetics, Behavioral; D005838:Genotype; D006801:Humans; D007223:Infant; D008297:Male; D011247:Pregnancy; D012737:Sex Factors; D012890:Sleep; D012919:Social Behavior; D013060:Speech; D014427:Twins