Why does yogurt increase my sex drive?

I know it sounds strange, but yogurt substantially increases my sex drive. I'm a middle aged male in good health, and when I eat several cups of yogurt it has an almost viagra-like effect on me. The only ideas I have about this is that it's either the extra calcium or perhaps hormones in the milk they use to make the yogurt. I don't usually eat any other dairy products most of the time.