Sexual desire have been associated with a decline in sexual desire. Though it is not used as medication, the drug methamphetamine has a strong positive effect on many aspects of sexual behaviour, including sexual desire. Sexual desire is said to be influenced by androgens in men and by androgens and estrogens in women. Many studies associate the sex hormone, testosterone with sexual desire. Testosterone is mainly synthesized in the testes in men and in the ovaries in women. Another hormone thought to influence sexual desire is oxytocin. Exogenous administration of moderate amounts of oxytocin has been found to stimulate females to desire
XX male syndrome gene on the Y chromosome is moved to become part of an X chromosome. The presence of the translocated SRY gene leads to an XX embryo developing male characteristics. In rare cases, an XX male does not have the SRY gene. The exact cause of this condition is unknown but it has been proposed that mutations in the SOX9 gene may contribute to this syndrome since SOX9 plays a role in testes differentiation during development. Another proposed cause is mutations to the DAX1 gene which encodes a nuclear hormone receptor. DAX1 represses masculinizing genes, therefore, if there is a loss