Is there such a thing as a 'gay gene'? Well, there's probably some kind of genetic factor. The latest thinking is that multiple genes - and not just the sex chromosomes - are important in sexual orientation, with environmental factors coming into play too.

The question of a gay gene may come closer to an answer with the imminent publication of a DNA study by scientists at Northwestern University. They're researching 800 sets of brothers to search for the specific genes that influence some brothers to be gay and others to be straight.

Many people would say gay-gene schmay-gene. As long as consenting adults are free to fancy each other with impunity, regardless of sexuality, what does it matter? A fair point.

In the USA there's already a law against genetic discrimination. The Genetic Information Nondiscrimination Act of 2008, aka GINA, protects Americans from being treated unfairly - eg by insurers - because of differences in their DNA that may affect their health.

If you're worried about an inherited genetic disease - or if you've been diagnosed with one - your GP can refer you to a genetic counsellor. Counselling could help you understand the nature of the disease, options for prevention or testing, the risks of recurrence and the implications for other family members.

December 2008: US researchers find evidence that homosexuality's linked to genetics

September 2008: Genetic test reveals patient has 60% risk of developing cancer again