Growth scan today

So today at 31 weeks 3 days they decided to do a growth scan to see how big baby is. They said he weighs 3 pounds 12 ounces and his arms and legs are a little on the short side, quickly after she said that she looked at me and my boyfriend and so Oh that's probably just genetics lol I'm only 5 foot 2 and my bf is only 5 foot 6 lol.