Talk:Edd/@comment-3501335-20110404040225

I think some fans think Edd has blonde hair is because one of the creators (Scott?) said that his theory was that Edd had blonde hair and didn't want to be stereotyped, so he wore a hat. Some fan automatically believed it as canon, making some other fan believe it as canon, and so on.

Source from random comments over the years, mostly on DeviantArt. Yeah, don't take my word for it.