Looking through the thread about Crusader Kings on a CK Reddit, I ran into the following throwaway comment:

The genocides, the murders, the marrying your grandmother and having kids........beautiful!

I know we discussed other weird marriages in this game here (" Is marrying my own sister a good idea? "), but can the game actually be practically played in a way that you can marry your grandmother and have kids? How?

  • 13
    This title is not what I expected to see on Arqade.. Commented Dec 18, 2015 at 14:59
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    @Gnarly404 Arqade is exactly what I expected when I saw the title.
    – user177
    Commented Dec 18, 2015 at 15:11
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    @MichaelT Crusader Kings is exactly what I expected when I saw that title. :P Commented Dec 18, 2015 at 15:17
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    From a gameplay standpoint, there are definitely cases where you would want to marry your grandmother for reasons other than having kids. If she is a ruler in her own right, the alliance could be valuable. If she has a claim and is of your dynasty, marrying her would bring her to your court and pressing her claim would make her a vassal - depending on the succession laws, this could make you the heir to an additional realm. Finally, if you have enough kids and she has amazing stats, that can provide an excellent boost to your realm.
    – Dacio
    Commented Dec 18, 2015 at 20:33
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    @MichaelT Y'know, I hardly know the game from the little bits and pieces I see around here, but I wasn't at all surprised to find out what it was either. Starting to think maybe I should give it a shot.
    – Iszi
    Commented Dec 19, 2015 at 5:51

2 Answers 2


In the best possible case, this would be the progression: Your grandmother, Alice, marries Bob at the age of 16 (minimum age) and has a child, Charlie, when she turns 17 say. Charlie marries at 16 and has a child at 17, you. At this time your grandmother Alice is 34 years old. By the time you turn 16, your grandmother will have turned 50. The game makes women completely infertile at 45 (see CK2 wiki), so you would not be able to have children.

Even if the people in the chain somehow managed to have children immediately after marriage at 16 (practically impossible) that would still make your grandmother 48 when you're first eligible to marry her, past her child bearing years.

  • 1
    Are there any mods that changes either the minimum age before being able to marry, or the maximum age that a woman is fertile? Maybe this is what this reddit user was refering to?
    – Laf
    Commented Dec 18, 2015 at 14:42
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    Good reasoning, although it doesn't preclude you from marrying your grandmother and having kids with someone else who isn't her.
    – Eric
    Commented Dec 18, 2015 at 15:36
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    I read the question as "is it possible to marry my grandmother and have children with her". OP can clarify if that's not what he meant, but seems like otherwise the answer is trivial.
    – SMeznaric
    Commented Dec 18, 2015 at 15:54
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    @JonathanDrapeau Marrying your grandmother is trivial, there's nothing stopping you from marrying a post-childbearing woman and a few religions have Divine Blood, which allows unrestricted marriage of family members. It's the having kids part that's tricky, as this answer explains. Commented Dec 18, 2015 at 16:14
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    Your first name picks are Alice and Bob. How do you not have any rep on Sec.SE or Crypto.SE?
    – Iszi
    Commented Dec 19, 2015 at 5:23

If you extend the definition to anyone who is your biological relative and also your grandmother by law, this becomes possible. If your dad marries a woman, has two children, you and one girl, then divorces her and marries the child while you marry your mother, your sister becomes your step mother, and her mother is your step grandmother, as well as your wife and mother.

However, divorces generally aren't that practical and usually completely tear apart the two families, but if instead your dad has you, and another woman somewhere else has a daughter at <20, you can do the same age swap as above and still end up being married to your step-grandmother.

  • I am pretty sure it means a grandma by law rather than biological grandma. As others have said, the math doesn't add up for biological grandma. But I actually once had a case of my 50 year old king had his wife died so he married a younger woman for her ridiculously awesome stats and traits. He died a year later, and she married his son, then a couple years later he died in war and she married his son. Then 10 years later she married his son as well. None of them were biologically related, just a lot of random luck causing death
    – taltamir
    Commented Feb 28, 2016 at 21:55

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