The Nature of Causality

Every now and again, I'll see some chowderhead gibbering on about how evil Teh Gayz are; and they'll babble about the spread of diseases (ignoring how rare it is for lesbians to transmit certain ones...); and they'll quote statistics of one sort or another about how homosexuals have a higher incidence of suicide and depression.

Well, I can't imagine why that might be. Can you?