Blood, what i mean to say is for eg. a young boy can have a crush on his teacher..who is way older to him, as he grows up he finds girls his own age more attractive, as he grows older, he starts looking for a specific things in a girl he can get along with. She could be the outgoing type, the shy type, the not so bright type, whatever it is.

For me I didnt look for a smart girl...she was smart enough to find me lol.