Beauty preferences, again

From the comments on the last entry on the same topic and from some live- and irc-conversations I figure most people's preferences don't change a lot over their lifetime. I wonder where the preferences come from, and how much of them are genetic.

Some things are sort of obvious, like the preferences for youth and health and strength and fertility, although with these I wonder about the existence of the people who do not prefer at least some of them - for example where do the women who do not prefer tall men come from? Or the men who prefer extremely thin or extremely fat women?

What is more interesting is how less survival-essential preferences come to be. What makes people select for a particular hair color, eye color, shape of the nose/mouth/cheekbones, hairy skin vs. smooth skin, etc.? How do preferences for unnatural things such as hairless faces on men and short hair appear?

I always found it a bit strange that people tend to have a strong preference for a body type, but I suppose it's me who is weird in paying so much attention to faces and so little to bodies. I have a sort of body preference - about 170-175cm tall and quite thin - but it's not a problem for me if a man is a lot thinner/fatter/taller/shorter than that. As opposed to, say, having a wrong kind of cheekbones, or way too much body hair. This face-centeredness unfortunately makes me very aware of how fleeting beauty is - it takes a lot to change one's body, but a very good-looking face can be made less-than-average-looking simply by failing to shave it for two months.