[Family background and behavior patterns of only or "non-only" children].
D002648:Child; D002652:Child Behavior; D002675:Child, Preschool; D005190:Family; D005260:Female; D006801:Humans; D008297:Male; D009863:Only Child / Q000523:psychology*; D012931:Social Environment; D011795:Surveys and Questionnaires