Newborns Legs too short?

Br

Hi all, just got back from my pediatrician appointment and the doctor is not concerned but mentioned that his legs were short and he was only in the 25th percentile for height. My family and my husbands family are all tall people (5’11 and taller) except for me and my mom (5’3). I know it’s not something to be worried about since dr didn’t say anything but my son has hypothyroidism which can affect physical growth. He’s 5 weeks old. TIA