Loving the game. One thing that would make it so much better is a genealogy chart. This would be a flow chart showing all the family trees accessible from the menu. It would make planning out the various pairings so much more interesting. Especially if you added mutations.
The chance of a mutation would depend on how closely the parents are related, and how much radiation exposure they have had. Mutants might be unable to work, yet still use resources. Or they might be savants in one area, but useless and untrainable in others.
With this I'm place you could take away the incist taboo. You could even have a random event where some love struck young couple sneak away and have an unauthorised pregnancy.