Why might someone have a high sex drive?

Genes, hormones,: hidden anxiety, drug/alcohol overuse--these are the kinds of things I first think of. There are some substances that seem to heighten sexual desire (Vitamin E does it for some but not others, and I don't know if this scientific...) and there are a host of touted products that increase sex drive, by advertising. (I'm suspicious that this is more advertising than fact, so check them out)