Sexual Orientation Genetic?

Scientists keep trying, but this quote is telling.

“Since sexual orientation is such a complex trait, we’re never going to find any one gene that determines whether someone is gay or not,” says Mustanski.

I’m not sure what the goal of this research is, but there is plenty of evidence that shows that homosexuality is not genetic (.pdf). Isn’t there a better way to be spending these research dollars? Perhaps cancer research?