There's a recent study that's all over the news about STDs in high school girls.
Evidently, one in four high school girls has a sexually transmitted disease. This is way up from the stats when, say, our parents were in high school, and even way up from when I was in high school.
So, I'm thinking, the younger the people you date are, the more likely you are to sleep with someone who has an STD (and keep in mind that most people who have common STDS do NOT even know that they do!)
However, the older the people you date are, the more partners that person is likely to have had. So, their chances of having an STD may be higher.
Therefore, the best conclusion, I've realized, is to date older prudes.