A LESBIAN couple in California who say their 11-year-old son Tommy wants to be a girl named Tammy are giving their child hormone blockers that delay the onset of puberty, so that he can have more time to decide if he wants to change his gender.

The couple's supporters say the Hormone Blocking Therapy has only minor side effects and is appropriate for a child who is unsure of his gender.

"This is definitely a changing landscape for transgender youth," said Joel Baum, director of education and training for Gender Spectrum, a California-based non-profit group. "This is about giving kids and their families the opportunity to make the right decision."

But critics of the treatment say 11-year-olds are not old enough to make life-altering decisions about changing their gender, and parents should not be encouraging them.

"It's like performing liposuction on an anorexic child," said Dr Paul McHugh, professor of psychiatry at Johns Hopkins University.

"It is a disorder of the mind. Not a disorder of the body. Dealing with it in this way is not dealing with the problem that truly exists. We shouldn't be mucking around with nature. We can't assume what the outcome will be," Professor McHugh said.

Dr Manny Alvarez, senior managing health editor of FOXNews.com, said the hormone blockers also may pose a medical risk.

"Potential long-term effects can include other abnormalities of hormones, vascular complications and even potential cancer. I think that if this child - as he finishes his puberty and teenage years - decides to undergo a transgender procedure, then there are proper channels to do so," Dr Alvarez said.

"But to do it at the age of 11, to me, could be potentially dangerous to the health of this child," he said.

Tommy's parents, Pauline Moreno and Debra Lobel, told CNN they support their child and feel this is the best way for him to find an answer to a question he has been asking all his life.

They say Tommy - whom they now call Tammy -- began taking GnRH inhibitors over the summer to give him more time to explore the female gender identity with which he associates.

Tommy began saying he was a girl when he was three years old, his parents said. He was learning sign language due to a speech impediment, and one of the first things he told his mothers was, "I am a girl."

The child's parents also said Tommy threatened to mutilate his genitals when he was seven, and psychiatrists diagnosed a gender identity disorder. One year later, he began transitioning to Tammy.

After much deliberation with family and therapists, the child began taking hormone blockers a few months ago. The medication, which must be changed once a year, was implanted in the boy's upper left arm.

Tommy will continue the treatment until he turns 14 or 15, at which point he will be taken off the blockers and pursue the gender he feels is the right one.

Originally published as Puberty stopped for child to pick gender