sheep, pigs and deers have split hooves...are they related?
Um, yes. They are members of the order Artiodactyla the even-toed ungulates and their relationship is supported by genetic analysis. You could add cows and giraffes to your list as well, not to mention camels and hippos.
Do you ever think to check these things out before you ask them?
perhaps the gene was rendered inactive once it was inserted into the mouse
Such mice are bred for more than one generation, if it was simply that the human copy was inactive in the mouse then you would tend to see no viable mice homozygous for the human version in later generations if it was an important gene.
have they tried this in the embryonic stages of life before the genes have had a chance to do what they were designed to do?
That is what they do, you can't make an adult transgenic mouse without having it grow from a transgenic embryo. The real trick is working out how to let you only activate the changed genes at later stages of development or in the adult.
TTFN,
WK