Inbreeding

[notahero]

So I've recently purchased CKII at long last, and in one of my saved games I was thinking on experimenting with Inbreeding by bethrowing the selected king to his sister (I was curious to see how the traits would go) however at least in the European section of the game where I currently play as the young king of France this doesn't seem possible, contrary to what a friend told me that it was.

So I'd like to ask, is it possible to bypass the 'no marriage to close relatives' rule or can inbreeding only be practiced under certain DLCs?

Many thanks.

[ShadoWwolF]

in game zoroastrians are the only ones able to marry their siblings

you could mod it if you really wanted to, or you can just settle for marrying cousins

[notahero]

So inbreeding is not possible at all no matter what unless the Zoroastrian DLC is purchased?

Mod it? What do you mean? (sorry I'm a begginer at this)

[ShadoWwolF]

Originally posted by hananawan:

So inbreeding is not possible at all no matter what unless the Zoroastrian DLC is purchased?

you can still marry other relatives just not siblings or your parents or children

[Corrupted Sanity (Vex)]

It looks like there's a console command that allows it - just open it and type "marry_anyone"

[Badass Fatass]

Also, there is no zoroastrian DLC. I think you need old Gods to play it.

[TM]

If you want to use brother-sister unions to try and make your inbred dynasty, you will need the Old Gods DLC so you can play Zoroastrians. But it's perfectly possible to create an inbred dynasty without that.

If you frequently marry into close family (marrying sons off to your nieces for example) over time you will probably start seeing negative health traits like clubfooted, harelip and suchlike turn up in your dynasty with greater regularity. Actually getting the inbred trait is rare, but when it happens you usually have someone who is not long for this world. They're all but infertile, terribly unhealthy and have big maluses on their base stats.

It seems fairly difficult to get the inbred trait though. You can increase the odds of getting it, but it is somewhat random. I tried for it in a restored Persian empire Zoroastrian game to try and get the achievement but I had no luck. Then in a different game not in ironman, where I never knowingly intermarried with my dynasty, I ended up with an inbred heir anyway

[Vargas78]

I'm pretty sure they develop weird traits anyway if they keep marrying cousins. Regardless if you have old gods or not.

[eXistenZ]

You cant marry close relatives, except when playing zoroastrian. But after a while you have some cousins or kinsmen/women you can marry.

Play muslim, you're allowed multiple wives, and one of them was a relative, i got two inbred kids and the achievement out of it. And open succession means you can still choose your heir

[Surimi]

It's also worth noting that Zoroastrians actually don't get inbred very often. They have a hugely reduced base chance to get the trait, and if you do what you're supposed to do (and have a whole bunch of genetically superior concubines for diversity) you might never see it. Zoroastrians have an increased chance to be insane however.

Your best bet is probably to marry cousins or other characters who are "close relatives" (bright red blood drop). However, bear in mind you really don't want this trait. It's actually worse than being an imbecile.

[Langkard]

If you want to get really deep into how the genetic system works, look at your save game file. You have to save it uncompressed (uncheck it in the box to the right of the file name before saving). Then you can open it with a robust editor. Don't bother with Notepad, it doesn't handle the file size. Wordpad works fine.

Each character in the save file has an item called dna which consists of 11 lower case letters. These letters are random for newly generated characters. It becomes important when two characters produce a child.

When two characters have a child, the DNA of the child will consist of 5 random letters from each parent's DNA strand, plus an 11th entirely random letter. If your line begins to accumulate too many of the same letters in the DNA, then it is becoming inbred and will start to have a higher chance of traits like idiot and ugly and so on up to insane and possessed and then the worst of all - inbred. Obviously if the parents are too closely related, they are going to have similar strands of DNA letters and that means the child is going to have a greater chance of duplicate letters in the DNA strand. Having 2-3 of the same letter doesn't seem to be all that bad, but once you start seeing 4 or 5 or more, then the chance of bad inherited traits increases dramatically and good traits become more rare.

http://crusaderkings-two.wikia.com/wiki/Breeding:_Eugenics_For_A_Better_Future

The above CKII wiki article explains it pretty well, but is a bit out of date in that the dna can now consist of any of the 24 letters in the English alphabet, instead of just 16 like it was when the article is written. This reduces the chance of inbreeding to some degree.

Exactly how the game parses the DNA strands is unknown. Paradox will only say that it affects breeding traits. The above information is all that we can be sure about. We don't know the percentages at which bad traits appear or how the game chooses which 5 letters come from each parent.

If you want to experiment, make sure you backup your save game file first. Then make some changes to a married couple (you can get their game ID#'s by typing charinfo into the console) and then search by that game ID in the save game file. For example search the text file for 507717= and it will find the character with that ID. Change the DNA strands for both prospective father and mother to make them more similar. Make them both xxxxxxxxxxx for example. Changing it after they've already been given their inherited traits (at birth) doesn't affect them. But with both identical, that means their child will have a guaranteed DNA strand of 10 x's plus one random letter. Now save the file and watch what happens when the child is born. He or she is almost certain to have bad genetic traits.

[ShockedAlien]

Inbred ... got that trait/achievement from marrying my well bred, genius ruler to a quick debutante (so no possible relation whatsoever). His other children were 2x quick + 1x genius (not sure if with the same woman).
All this while unsuccessfully trying to breed children with bad congenital traits to marry them off to a foreign dynasty.
Now that I'm thinking of I'm wondering if there are genetic factors that define the gender of a child. I had a muslim ruler who had like 12 daughters in a row from 4 women but no son until he settled for a one time affaire and promptly sired a strong bastard son who didn't have any trouble of siring sons. So either there are hidden mechanics working that I don't know or fortuna has a strange sense of humour.

[Corrupted Sanity (Vex)]

Originally posted by Fjoel:

Inbred ... got that trait/achievement from marrying my well bred, genius ruler to a quick debutante (so no possible relation whatsoever). His other children were 2x quick + 1x genius (not sure if with the same woman).
All this while unsuccessfully trying to breed children with bad congenital traits to marry them off to a foreign dynasty.
Now that I'm thinking of I'm wondering if there are genetic factors that define the gender of a child. I had a muslim ruler who had like 12 daughters in a row from 4 women but no son until he settled for a one time affaire and promptly sired a strong bastard son who didn't have any trouble of siring sons. So either there are hidden mechanics working that I don't know or fortuna has a strange sense of humour.

IIRC it's basically just a coin flip made when the child is born - I know you can save just before the child is born and reload to get a different gender