I'm 20 years old and I'll be 21 soon, but people think I'm about 16. I seem to be stuck at this age. When I was actually 16 people thought I was about 14/15, not much of a difference but almost 5 years have passes and people still think I'm around that age. People around me even say I look young. For example my younger sisters friends, (they really are 16/17) all say I look their age and to be honest if you saw us out together you'd think we were in the same age group. Then two weeks ago I went to a pet store to buy a budgie with my sister and the sales women asked me for my age and didn't believe me when I said 20. I guess I'm not too bothered about it, I mean it sort of points to the idea that I will continue to look young when I'm older (hopefully). But what confuses me is why I seem to be not ageing when most people I know look their age and a few look a lot older than their age. I mean looking back at my classmates some of them have aged pretty quickly. One guy who I had a huge crush on (for a very long time when we were back at school) looks terrible for his age, and this guy was gorgeous, all the girls thought so and boys were jealous of him. It's crazy I hadn't seen him in years and then I did and he was just so different. I stayed the same but he looked as though he aged 10 years. Then my younger sister looks her age always has, soon people will think she's the older one.

I don't really exercise, my diet has only recently become healthy, I had no skin care process till recently, I don't wear make up I don't drink or smoke and I grew up in London (so not the most clean environment) and only moved recently to uni.

My dad has always looked good for his age, but physically I seem to resemble my mums side of the family so I don't know if his genes have anything to do with it, and my mum's side of the family look their age or older. So why is this?