Gender identity disorder a person experiences psychological dissatisfaction with his or her biological sex. Sexual dysfunction people who have this, find it difficult to function adequately while having sex. Paraphilia includes disorders in which sexual arousal occurs primarily in the context of inappropriate objects or individuals: para attraction is abnormal, philia strong attract or liking. More common among monozygotic twins (identical) than dizygotic twins (fraternal) or natural siblings. When a person"s physical gender is inconsistent with that person"s sense of identity. People with this disorder feel trapped in a body of the wrong sex. Primary goal is not sexual but rather the desire to live openly in a manner consistent with that of the other gender. Independent of sexual arousal patterns: male-to-female transsexual, may be sexually attracted to females, which technically, makes his arousal homosexual. Slightly higher levels of testosterone or estrogen at certain critical periods of development might masculinize a female fetus or feminize a male fetus.