They actually look Recessive to me. That being said, unless you know the genetics, it can be a guessing game.
Recessive lose all of their at around 4 weeks. vs. Double Rex who generally keep "peach fuzz" on their face, feet and base of tail.
True Recessive Hairless should be completely bald by eight weeks of age (some keep a level of "peach fuzz" though). Sometimes they even lose their whiskers (which is show standards). As babies they might have a thin layer of fur, but generally by six weeks of age, they should be pretty much bald.
For breeding your better off with them being double rex. True hairless don't do well although they are neat. Grow one up breed it to a normal and you should get rex babies if they are double rex.
looks like you had the true hairless gene in your breeders. Where did you get your stock?
Got a lot of my stock from a pet store going out of business. That may explain it, huh. I really don't want anymore, I have heard (no idea if it's true) that they are not as nutriential as regular rats & they are too darn cute to feed off!! I will end up keeping every one of them as pets. I have actually produced one more before these but he died very young, like 3 weeks. He was completely bald. Bottom line is I have atleast 2 het hairless rats producing hairless and 66% hets?