Yep my 'natural' bodytype was skinny/fat (ecto/endo mix). How much of this was because of my crappy eating habits + genetics who knows. 3 or 4 bowls of cereal for breakfast, snacking on cereal later on, that was my habit as a kid.
It could also be water retention, but if diet wont fix it then its genetic. Some people also just have, big heads. I'm not making a wisecrack.