title: Is sexual preference determined by heredity? Introduction.
mesh_terms: D005075:Biological Evolution; D012734:Disorders of Sex Development / Q000235:genetics / Q000523:psychology; D005260:Female; D018452:Homosexuality, Female / Q000235:genetics* / Q000523:psychology; D018451:Homosexuality, Male / Q000235:genetics* / Q000523:psychology; D006801:Humans; D008297:Male; D012723:Sex; D018433:Twin Studies as Topic