Why do gay teens commit suicide at far higher rates than others?

Nobody seems to ask the question why it is that gay teens commit suicide at far higher rates than others. It can't be the bullying - the high rates of suicide by gay people persists in societies such a Sweden where the gay lifestyle is much more accepted than here. To say that bullying causes it is a popular thing to say. But gays are not the only ones getting bullied. There are many different groups that get bullied, but who do not have the higher rates of suicide. Why?

Is anyone game to do a serious study on what are the causes of this high suicide rate? Remember that correlation is not causation. We are looking for what is causing the high suicide rate. Because until we know the causes we cannot effectively deal with the problem.

I reckon we owe to the gay young people out there who are suffering to find this out so that we as a society can help them.