I've seen a lot more small hairless. It might have something to do with hairless rats being bad mom's in general sadly enough. But yeah there are two hander hairless rats, they just don't seem as common.
It might also be hairless havn't been bred for lab studies on diabetes and for feeders as often. I know a lot of pet store two handers come from lab bred stock, or so my vet tells me. And they are continued to breed larger for snake food. I don't think they do this with the hairless genes as hairless sell pretty well as pets.
It's sad but that's the reality I geuss. I love Bert and he is definately the smallest male I've owned out of the six rats I own and have owned.
although picasso and mozart are still practically babies, picasso is about 2 months older than mozart, and mozart is definitely the larger of the two. it could have something to do with hairless genetics and that many genes code for more than one thing, and breeding for no hair may have bred out efficient feed to gain ratios, etc. dunno, but i def think that as a majority, hairless are smaller in general.