President Barack Obama recently called for a nationwide ban on minors receiving controversial gay conversion therapy. He said: "Tonight, somewhere in America, a young person, let's say a young man, will struggle to fall to sleep, wrestling alone with a secret he's held as long as he can remember."

The proposed ban is known as Leelah's Law, named after transgender teen, Leelah Alcorn, who committed suicide last December. Valerie Jarrett, a senior adviser to the president, slammed the therapy in a statement: "The overwhelming scientific evidence demonstrates that conversion therapy, especially when it is practiced on young people, is neither medically nor ethically appropriate and can cause substantial harm." 

So is there any scientific support for interventions that attempt to change the orientation of gay, lesbian and transgender people?

The American Psychological Association (APA) would say no. In 2009, an APA task force reviewed all the studies from the 1960s to 2007, finding that sexual-orientation change most uncommon. While most interventions today focus on 'talking the gay away,' some psychologists used to administer what's known as aversion therapy, where gay people were given electric shocks or nausea drugs while watching same sex porn. A few studies found this reduced their sexual response to same-sex pornography, but didn't affect their sexual orientation.  

"Unfortunately, much of the research in the area of sexual orientation change contains serious design flaws," said psychologist Judith Glassgold, who chaired the group. "Few studies could be considered methodologically sound and none systematically evaluated potential harms."

The report also found that some gay conversion therapies could have negative consequences, including cause anxiety, depression and suicidal feelings.

Speaking to the BBC, journalist and gay rights activist, Patrick Strudwick, described how a gay conversion therapist told him it was "very likely" that he'd been abused by a family member. "I was advised to have regular massages with a male masseur as a way of having non-sexual contact with another man, therefore fulfilling the side of me that craves that kind of intimacy with men," Strudwick said. "I'm afraid to say everyone who I have met with, who has been through any form of conversion therapy or aversion therapy, has been severely affected for a long time."

But there is cause to believe future interventions may be more effective. "Based on current scientific research, it is not unlikely that medical researchers - in the not-too-distant future - will know enough about the genetic, epigenetic, neurochemical and other brain-level factors that are involved in shaping sexual orientation that these variables could in fact be successfully modified," wrote neurophilospher Brian Earp from the University of Oxford and science ethicist Andrew Vierra, of Georgia State University, at The Conversation.

Earp and Vierra point to a number of possibilities. Firstly, 'anti-love biotechnologies' might reduce, rather than re-orient, same-sex love and desire by interfering with how the brain processes lust, attraction and attachment. In effect, they say the drugs would dampen one's libido, chemically blunting any same-sex desires. 

There's also the possibility scientists may find a way to directly affect orientation. "All animal behaviour - including human behaviour - is at least in principle reducible to brain states," they write. "It then becomes a matter of figuring out which specific brain-based manipulations would work to alter the higher order drives and capacities that govern one's sexual orientation."

There are a couple of aspects to science that make them think this is so.  

Firstly, gay men and heterosexual women share a number of traits, including the length ratio of their index finger to ring finger and certain aspects of bone structure. Scientists think these characteristics come about as a result of exposure to androgens or certain other aspects of the amniotic environment. Presumably, as science learns more, they could learn how these aspects could be manipulated. And a genetic analysis of 409 pairs of gay twins late last year linked male homosexuality to two specific regions on the human genome, suggesting that some kind of genetic factor is involved. 

Earp and Vierra think this could spell danger for the current 'born this way' gay rights movement: "This has become a lynchpin in the fight for gay rights. 'Since I can't change who I am,' many gay people have argued, 'it isn't fair to discriminate against me.'"

Regardless of the possibilities for changing human nature, that doesn't mean that it would ever be ethical to try to do so. And when it comes to today's gay conversion therapies, it's very clear that they're an unnecessarily harmful waste of time.