Age gap

Is it wrong that I am 29 and my bf is 20? We've been together nearly 2 years and his family accepted me straight away he is brilliant with my boys, sometimes we get looks and ppl comment on how young he looks and embarrassingly he's been mistaken for my brother and son before. 
I'm happy with him and age is just a no but I'm just curious to hear your thoughts. Cos always felt like judged.