i know i dont have any dd but i got mine at 13and a half and my mum got it at 14 my sister was about 12 but she weighed more than me both mum and i were skinny where my sister was a little chubbier my bff didnt get hers till 16 but she was told by the doctor that she had to weigh at least 45 kg for it to happen she was really skinny and still is