Perceptions of alikeness and attitudes toward being a twin: comparison of identical and fraternal twin pairs.
D000293:Adolescent; D000328:Adult; D001290:Attitude; D005260:Female; D005306:Fertilization; D005838:Genotype; D006801:Humans; D008297:Male; D010063:Ovum; D011247:Pregnancy; D012649:Self Concept; D012737:Sex Factors; D011795:Surveys and Questionnaires; D014427:Twins