Genes, how much sun exposure you have, and weight.
I am currently in the south of France staying with someone who is 2 years older than me but she thought she was 10 years older. She has lots of deep lines on her face, but has lived here all her life and goes to the beach every day from May to September. She spends plenty on creams and potions, though, I have seen her bathroom!
I am a few stone overweight and all the fat on my face fills out my lines!I I really have no wrinkles at all, except for a few crows feet, and I am 52. However, being overweight is very ageing in itself and I would far rather have the slim size 10 body of my French friend
.