I believe everybody has a 'type'.
My type has been exactly the same ever since I first started to notice the opposite sex - I suspect I'm far from alone in this and therefore I would suggest what we find attractive is hard-wired.
Attraction, first and foremost, is always physical - some people always say that its the personality that counts, which is true, but more often than not the attraction to a personality follows a physical attraction (if you meet somebody in a bar you find physically attractive, at that stage you do not know their personaility).
I have been accused in the past of being 'shallow' because I don't find fat women attractive. A fat woman may have the greatest personality in the world, but as fat women are not my 'type', then the liklihood of finding out what their personality is like is (forgive the pun) slim...........and even if I did like a fat person's personality, the physical attraction wouldn't be there because she would not be my type.
This is not shallow. It is something I have no choice over.