One study published in the International Journal of Transgender Health found that in 20% of identical twin pairs, if one twin was trans, the other was as well, compared to only 2.6% of non-identical twins where this was the case; researchers attribute this to their shared genetics.Sexologist Ray Blanchard created a taxonomy of male-to-female transsexualism that proposes two distinct etiologies for androphilic and gynephilic individuals; this taxonomy has become controversial, supported by J. Michael Bailey, Anne Lawrence, James Cantor and others, but opposed by Charles Allen Moser, Julia Serano, and the World Professional Association for Transgender Health. Focus on trans women over trans men
Historically, formal efforts by the medical community to provide transsexual healthcare were extremely focused on transsexual women, with little thought for transsexual men. Julia Serano suggests that effemimania (the idea that male femininity is more psychopathological than female masculinity) was the driving factor. She sees this as a kind of transmisogyny (hatred of trans women as an extension of sexism). : 126–127  This effimimania conflates male homosexuality, MTF transsexuality, and feminine gender expression, while treating them all as a disease. : 129  She points to the medical communitys long love of now outdated theories such as autogynephilia. : 131

Medical assistance
Individuals make different choices regarding sex reassignment therapy, which may include hormones, minor to extensive surgery, social changes, and psychological interventions. The extent of medical intervention is a highly personal decision: there is no one-size-fits-all solution. Hormone replacement therapy
Transsexual individuals frequently opt for masculinizing or feminizing hormone replacement therapy (HRT) to modify secondary sex characteristics.
Some people have had sex reassignment surgery (SRS) but do not meet the above definition of transsexual. Other people do not desire SRS although they meet the other elements of Benjamins definition of a "true transsexual". Transsexuality was included for the first time in the DSM-III in 1980 and again in the DSM-III-R in 1987, where it was located under Disorders Usually First Evident in Infancy, Childhood or Adolescence. Beyond Benjamins work, which focused on male-to-female (MTF) transsexual people, there are cases of the female to male transsexual, for whom genital surgery may not be practical. Benjamin gave certifying letters to his MTF transsexual patients that stated "Their anatomical sex, that is to say, the body, is male. Their psychological sex, that is to say, the mind, is female." Starting in 1968 Benjamin abandoned his early terminology and adopted that of "gender identity." Medical diagnosis
Transsexualism no longer is classified as a mental disorder in the International Statistical Classification of Diseases and Related Health Problems (ICD). The World Professional Association for Transgender Health (WPATH) and many transsexual people had recommended this removal,: 743  arguing that at least some mental health professionals are being insensitive by labelling transsexualism as a "disease" rather than as an inborn trait, as many transsexuals believe it to be. Now, instead, it is classified as a sexual health condition; this classification continues to enable healthcare systems to provide healthcare needs related to gender. The eleventh edition was released in June 2018.