The addition of a DSB in the cast often adds a foreign flavor to the show, and it is not uncommon for the DSB to be of uncertain or dubious origin. The fact that very few people in real life have this natural combination of hair and skin helps to create this impression, with the exception of surfers or others who spend lots of time in the sun, as the sun bleaches hair and darkens tans, sometimes to extreme degrees. It's also common for a DSB to be of mixed heritage and have their appearance handwaved through this, but more often than not, it just goes unexplained; light hair on dark characters is simply easier to draw and frames the face very well.