• We have updated our Community Code of Conduct. Please read through the new rules for the forum that are an integral part of Paradox Interactive’s User Agreement.
As far as I know, this theory has already been refuted and it was stated that those DNA strings are used for portraits only.

Correct. Congenital traits are inherited based on a pure percentage chance defined in crusader kings ii\common\traits\00_traits.txt (or another trait file in the same location) and looks like this:

Code:
	birth = 50
	inherit_chance = 25

Where the first is how many children in 1.000 are born with the trait spontaneously and the latter being the percentage chance of it being inherited.

There's also
Code:
agnatic = yes
which gives 100% inherit chance from the father.
 
The basic genetic theory that all genes are in pairs. Each gene has different types, say blue eyes versus brown eyes verses green eyes.

One gene is always (well, not always, but usually) stronger than others, meaning that it is the shown trait if both are present. If "A" was brown eyes and "a" blue, everyone with a AA or Aa code would have brown, blue only showing up on "aa", but allowing the gene to still be passed on. This is the whole skipping a generation thing.

Here, he is showing the possibility for any particular gene combination to show up throughout the family, as long as the original ancestors had one parent with the AA and the other with the Aa codes in whatever trait is being tracked.

The only problem I have with this is he assumes the outsides in the family (Christian II of Denmark, Isabella of Portugal, etc) would automatically be AA, which can't be right.

Oh, yeah, I'm aware of the basics of how recessive and dominant genes work - sorry I didn't make that clear (I did survive high school science classes!), but I was confused about what this tells us about inbreeding or the chances of getting bad genes.
 
Oh, yeah, I'm aware of the basics of how recessive and dominant genes work - sorry I didn't make that clear (I did survive high school science classes!), but I was confused about what this tells us about inbreeding or the chances of getting bad genes.

I think the bad gene was aa, which he had a 1% chance of getting, but it would add up for multiple genes
 
I once tried to make an dynasty of imbeciles and inbreds. I discovered a woman fit for my king, as there were no suitable candidates from his own dynasty. She had the inbred (or was it imbecile?) trait. But what do you know! They had three children two sons and a daughter and they were all geniuses!

At least in real life, no matter how inbred you are, it won't be passed on to your children at all if you have children with someone you aren't related to.