Take a look at this page from my Super Street Fighter 2 manual.

In particular, check out the entry for 'blood type'. You might look at that and think, "Why would I care about that? I'm not going to be working in a fictional hospital where this fictional guy might go to get treatment." But there's more to it than that.

If you dig enough, you can find blood types for lots of characters, not just Street Fighters.

But why?

It turns out that there's this theory in Japanese culture that different blood types have different personality traits. For instance my blood type, type O, says (from this site) that I'm

"People with blood type O people are outgoing, energetic and social. They are the most flexible of the blood types. They easily start up projects but often have trouble following through because they give up easily. They are flighty and not too dependable. O types always say what's on their mind. They value the opinion of others and like to be the center of attention. Also, people with O blood are extremely self-confident."

Does that describe me? Kind of, but then again, so do parts of the others. So, take the profiles with an appropriately-sized grain of salt.

You can get more info at Wikipedia.