Gender Identity is Biological, Study Says

— -- There is growing body of evidence that gender identity is hard wired into the brain and not simply a matter of psychology, according to a new Boston University School of Medicine study.

Writing in the journal Endocrine Practice, the researchers said that as many as one in 100 people could be living with some form of gender identity disorder -- meaning they may identify their gender differently than the one they were born with.

For example, actress Laverne Cox was born a man but identifies as a woman.

This makes the case for doctors to use surgery and hormone treatment rather than psychotherapy alone to help their patients come to terms with their gender identity, Dr. Joshua Safer, the lead researcher and a professor at BUSM, said.

“The paper was a comprehensive review of the scientific evidence that gender identity is a biological phenomenon," Safer explained. "As such it provides one of the most convincing arguments to date for all medical providers to gain the transgender medicine skills necessary to provide good care for these individuals," he added.

Nearly 40 percent of medical students they surveyed said they were uncomfortable caring for transgendered patients, and 5 percent of medical students said that the treatment was not part of conventional medicine. After teaching a course that raised the medical student’s awareness about transgender medical need, the students discomfort dropped by 67 percent.

Safer and the other authors of the study said they hope to change the perception of transgendered people within the healthcare system so that they get better treatment. But because the study was small, it does have limitations, the researchers said, and there should be additional investigation to focus on the specific biologic mechanisms for gender identity.

The ABC News National health team would also like to raise awareness about gender identity and what it means to be transgendered. We’re holding a tweet chat on the topic March 10 at 1 p.m., ET. Dr. Richard Besser, ABC News chief health and medical correspondent will moderate. We’ll be joined by experts, patients and loved ones to talk about the challenges of being transgendered and what that means for overall health and wellbeing.

Joining the chat is easy. Click here to learn more.