I am not a lesbian, or a female, but I always had this question..

I hope this doesn't come off wrong, because I'm just curious and this question has never been answered before. I understand human sexuality and attraction are very fluid subjects, and they very greatly from person to person, but why do some lesbians go for the butch type? Why do some females dress butch? Why would someone who says they're attracted to females, be attracted to masculine-looking females, or dress in a masculine way but wish to identify as a female?