They are not as sensitive to the wounded toxin. Stress increases the chance of mutation in their offspring's genes. They have a reduced susceptibility to antigens and glycotoxin.
They walk differently when aroused or when drunk.
Toxins and antigens decay faster.
When norns are hit, or when they fall, or wallbonk, they recieve less of the wounded toxin.
They have a higher concentration of antibodies at birth.
They have "Ac6" - "I have teleported", which is used by the DS portals. This wipes out their boredom, crowdedness, and pain. They have instincts to use portals when bored, crowded or in pain as well. While it is a very strong stimulus, it takes time to work fully - this explains why when you get cute norns warping in via portal, they often just stay for long enough for you to catch a glimpse of them before warping right out again. Try the Dummy Portal if you'd like to see this in action without losing all of your norns to the warp.
Chichis have an instinctive affinity for machinery - such as the Holistic Learning Machine or Portal Dispensor - rather than tools, which is what the C3 powerups are called.
The full gene compare can be downloaded at Exploring the Ark.
If there are any errors or omissions, please let me know in the comments!