Inbreeding mice
Inbreeding is not entirelly a horrible concept.. The problem with it occours when a specific animal, of any type is carrying poor genes.. Dominant or recessive, they'll be coming out full force. Put it this way, if you had a great breeding stock with flawless genes, and you only bred say six of them together for the rest of their lives, then bred their offspring together and so on; you'd have perfect animals forever.. However, since rodents are probably (an understatement) the most prolific mammlas, it would be almost impossilble to propose you are actually dealing with a perfect set of animals. But to me, it boils down to this.. your snake is going to eat them and gain the most nutritional benefit it can from that animal, calcium from its bones, whatever is in its stomach, protein from its muscle etc... so, keep them on good feed.. breed the heck out of them and stop worrying.. I've never had a problem anyway.. Hope that helps..