Now that I think about it, that is definitely true, at least for me. My two most powerful D&D characters ever were a Human and a Half-Elf. And most of my other characters have always been either Human, Elf, or Half-Elf. I never really thought about it before now, but yeah. When I have played oddball characters in the past (I once played an Orc Ranger named Schultz) I always had to make more of an effort to get the feel for them, and they never did seem as real to me. Huh, go figure. I guess the old adage is true: Write about what you know. It's true for novels, and for character backgrounds, it would seem.