Hi was interested to know where you found this information. Obviously in humans testicles in young boys can go up and down and there is an operation where a stitch is put in to prevent it going back up. Only know this as a friend's son of 8 had this done.Its not only genes that cause this issue either.whippets (and any other breed of dog) wouldn't exist if people hadn't bred dogs selectively -- better to select for health than for some of the strange things like the extreme pushed in faces of pekingnese and pugs for instance
I wouldn't think the genetics of cryptochidism was simple. I expect there is more than one gene involved and that environment plays some role as well as inheritance. There is more than one reason testicles don't descend, although short cords seem to be the most common problem. I'd be interested in links to info on research into crytochidism. There was an item on k9 a few years ago about ongoing research at Cornell Uni in the US into genetics of cryptochidism in dogs. I haven't heard whether the researchers have reached any conclusion.
Macha theres some interesting research about a link between zinc deficiency and retained testicles. Zinc supplements are sometimes given to young boys who have this issue (which is apparently more common than most folk think) with some success.