Use of drugs is far higher among gay men than it is among heterosexuals. This is largely because of the growing phenomenon of "chemsex" in major cities - i.e. a scene which overwhelmingly concerns single gay men who are outcasts.
The reason for this isn't because gay men don't have children, because children are disgusting - and it is quite possible and desirable to be childless and happy. It's because they often hate themselves, having been thrown out or disowned by their families (which happens far more often than people think it does) or discriminated against, or threatened (again, more common than people think). There is also a very significant social pressure on the gay scene to get p155ed/stoned and use drugs, which is perhaps a more intense manifestation of club culture. Hopefully this will all decline over time, but I don't really see a solution other than to provide education, decent public health services and just wait it out.
- Signed, a teetotal homosexual who has never touched an illegal drug - or been drunk. Ever.