I'm thinking sexual orientation is largely determined by nature rather than nurture. However other stuff like fetishes and such I think develops over time.
Porn related:
When I started watching porn I went for the standard playboy type girls, thin models ect, then later on big boobs fake or real I didn't really care. Now I really like natural girls and girls that have a little bit of weight on them, like Gianna Michaels. And I do occasionally watch bigger models like Samantha Anderson.
Non Porn related:
My first gf was quite slender, large natural breasts, second was a little heavier with big breasts, later I dated a very slender girl with very small breasts, and later again a slightly heavier girl with small breasts. Now I have a GF that is above the "slightly heavy" range with large breasts that is trying to lose weight, and right now I really don't care about her weight as long as she is healthy.
My tastes have also changed from BDSM to more TLC type sex. I used to have a big thing for girls in fishnets as well.