One obvious enhancement is extra brain power. They learn faster, remember longer and adapt to changes better than any ordinary mouse. This stuff boosts the cellular switches that help the brain store associations. While a human brain is more complex than a mouse's, the basic machinery of learning may be pretty much the same in both. Even selecting a child's personality in advance might be possible.
Experts believe that half of people's personality traits are hard-wired by their genes.
Of course, lots of genes combine to create any individual's melange of quirks and temperment. So building a child with, say, David Letterman wit, Mother Theresa compassion and Warren Buffett business sense may not be real easy at first. Still, scientists are laying the foundation. In mice, at least, they have already tracked down genes that influence many habits, including aggressiveness, overeating and mothering instincts. As fascinating as mouse personalities may be to scientists, soon there should be much more information about the genetic underpinnings of such things in larger, less furry creatures.