I can't comment on the upper body development seeing as I'm still newbie-ish to BB, but looking at the legs I would say they could be natural !!!
I did ballet since the age of 2, and my legs by the time I was thirteen looked just like that !!! (meant I couldn't be a ballerina though - TOO BIG !!). I was also a vegan so my protein intake at the time was probably about 10-15g per day. Go figure.
Even now, (I haven't been able to workout for 3 months...sob....due to work etc) I still have calves the size of grapefruits, and have lost hardly any muscle.
This I put down to my activities as a sprog having a direct effect on how my body now works and good genetics from my dad (He's never worked out but is 5'8'', 16 1/2 st and 15% bf. Only has to look at something heavy and puts on weight !!!)
So I would say it's natural.