STDs are so normal in Albion, that every human body is used to it. In fact, some bodies had so many STDs, and certain genes already inside them, that they altered the humans in a good way. Eventually, to people produced William Black, and their STDs affected him in such a way that he gained special powers, such as lightning. These powers became known as Will Powers. By now, they aren't really STDs anymore, because it's embedded in the hero-genes in such a way that they are good. Therefore, the hero starts of with 0 STDs. Any STDs you gain are strange to the body, so you they don't benefit you. However, you are still used to having them, so it also doesn't affect you in a bad way. Still, after several generations, they may do something with the new heroes, yet again... Only time will tell.