Behavioral characteristics of twins.
D000328:Adult; D001724:Birth Weight; D002652:Child Behavior; D005260:Female; D006801:Humans; D007223:Infant; D007360:Intelligence; D007361:Intelligence Tests; D008297:Male; D008423:Maternal Age; D011247:Pregnancy; D012959:Socioeconomic Factors; D014427:Twins