Why is it I am like a mother to my friends?

I am 13.My friends are immature.But I still love them(brotherly/sisterly)I am constantly telling them what to do and what not to do.It's like they don't know what to do without me.I don't mind it,it's just I don't know WHY they do it?Is it a good thing or a bad thing to be like a mother to your friends?