Numerous traits in Crusader Kings 2 can pass down when having children [Ugly, Genius, Quick, Attractive]. What are the odds of passing down these traits? Is it worth it to try to marry into a duplicate trait [Marry a genius to a genius]?
1 Answer
Most physical traits have approximately 15% chance of being inherited.
Even with two genius parents there's no guarantee that you'll get a genius as your first-born son, but if you have several sons, the odds of at least one of them being a genius are moderately high (~66% in this scenario with two genius parents and three sons born).
To answer your question, yes, duplicate traits are more likely to inherit. Likewise, if you have negative traits, you can decrease the chance by marrying someone with an opposite trait (e.g. quick counters slow, strong counters weak).
Negative traits can also be avoided by not marrying close relatives. It's generally assumed that it's safe to marry someone who shares grand parents, but the more you interbreed, the more complicated it gets.
Random chance also plays in. It's entirely possible to get traits neither you, or your immediate ancestors have.
If you want to learn more about the dynamics behind breeding, check out Breeding on Wikia.
For tables on which traits have what chance of being passed down, check Breeding on CKII Wiki.
