I am fairly sure that you can breed the tailess female mice. The guy who I got some of the mice from loves tailess and tends to keep them to breed to get more tailess. That is where the half tails come from. 1 tailess gene and 1 tailed gene. Now I must be honest and say that I have not SEEN tailess, but I really LOVE tails, so I think I would not like tham as much. I love when their tail wraps around your finger. (I also love cat tails. Wouldn't prefer Manx cats).