While I support Professor Chong Siow Ann's call for parents to respond sensitively when they first learn that their child is gay ("Coming out: How parents react is crucial"; last Saturday), there was incomplete information in his commentary that could lead readers to conclude that gays are born that way.

First, Prof Chong mentioned neuroscientist Simon LeVay, who in 1991 published results of a brain study on a group of homosexual and heterosexual men.

However, this study was done on just 35 cadavers, and Dr LeVay himself could not conclusively say if the tiny differences he found in the 35 brains' hypothalami were a result of homosexual behaviour or the cause of it; nor if those differences were caused by brain damage from those men's active HIV infections.

Also, Dr LeVay's study was never repeated by another researcher, but because it fulfilled the media's desire for news that supports sexual liberation and gay activism, it made headlines around the world.

Ten years after his study was released, Dr LeVay was quoted in a magazine as saying that research like his was often politicised.

He said: "It's important to stress what I didn't find, I did not prove that homosexuality is genetic... I didn't show that gay men are born that way, the most common mistake people make in interpreting my work."

Second, Prof Chong concluded that since "sexual orientation represents a highly complex behavioural trait with multiple determinants, including genetic and hormonal factors interacting with one another", this meant that homosexuality is an inborn characteristic that is "involuntary in people and is, therefore, not a matter of choice".

But what about other "multiple determinants" such as media, social, parental, experiential and peer influences, all of which feature far more prominently during an individual's formative years, which is usually when signs of homosexuality surface?

Finally, Prof Chong noted that most mental health organisations have "renounced the idea that homosexuality per se was something that could or should be cured or corrected".

But what should also be added is that while genetics are an indirect influence, they do not force people into homosexuality.

There is also documented evidence of former homosexuals who have successfully renounced their gay lifestyles.

Kelvin Seah Lee Nguon