I’m not saying this to be a pervert or anything, I am simply being realistic. The apocalypse has happened and few people are left, sooooo eventually after you are set up and safe enough it would make sense to eventually er, ‘make love,’ if nothing else but the continuation of the human race. Either you have kids or you clone yourself (Which I don’t think has been invented yet, Right?).
Also, I feel like NPCs should get traits, and your children would get a mixture of the mother’s and father’s traits (With a small chance of unique ones, or at least as they age.) I imagine that to make it no too much of a waste of time, it would take like two or three season for the child to at least reach teen level. And what would also be cool, is if you die you can choose to be your child rather than a brand new character.
There is of course the part of them being WILLING also. If you assist someone a lot it would make sense they they would be more willing, and maybe a relationship thing can happen in more detail. Speech skill and traits/mutations will also matter to some extend. Why would a normal human be easily willing to sleep with someone who has fangs, a tail and fur? Also, a new starting trait possible would be cool, something like ‘non-racist’ as a positive (And for realism ‘racist’ trait as bad) Also, once again for realism, the option of character gen would be your skin color (Which also factors into what can happen to NPCs) You could simply have neither and be neutral toward any skin color too. You COULD add rape, but me being a major hater of that (Cuz it is messed to a very large margin) would prefer not. But of course, realism.
Realism type things have been added quite a lot in CDDA as of late if I recall, but you detailed you would want to go is up to you.