Double First Cousins = Half Siblings

[RetroFan]

One learns something new every day, and I recently found out that double first cousins and half siblings share the same amount of DNA, something I had never heard of before. You probably are aware of what double first cousins are, they come about when their father and mother have respective siblings who also have children. For example, brothers John and James meet, fall in love with and marry sisters Cathy and Claire, both couples having children. John and Cathy's kids and James and Claire's kids will be double first cousins, and they will also share the same set of grandparents (something I did know beforehand).

I've heard that while some jurisdictions allow first cousin marriage, they specifically prohibit a marriage between double first cousins because they are so closely related genetically. And maybe dim-witted Karen Smith from Mean Girls was really on the right track when she was explaining to a very disturbed Gretchen that it was okay for her (Karen) to flirt with her first cousin, because you have your cousins, then your first cousins and then your second cousins. Perhaps the mysterious 'cousins' Karen spoke of are double first cousins?

So therefore if you by chance come across a double first cousin story in Incest Taboo, you are effectively reading a half sibling story. Two of my stories are about double first cousins. Ian and his twin sister along with Becky and her younger brother are double first cousins in 'Banging Cousin Becky In Blackpool'; while in 'Triple Fun For The Triplets' the titular triplets identical mirror image twins Chloe and Holly, their fraternal triplet sister Lindsay and their brother Brandon are double first cousins with Justin and Adelaide. That puts the 'kissing cousins' aspects of both stories on par with my story 'Exploring With My Big Brother', where 18-year-old Matilda loses her virginity to her 40-year-old half-brother Tyler when they go urban exploring at an eerie abandoned theme park.

I've already noted that half sibling stories are rare compared to full or step-sibling stories (adopted or foster sibling stories seem rarer still), but I can't imagine there would be a lot of double first cousins stories either. Have you ever written one, or read one? And if you did write a double first cousin story and someone comments that cousin stories are not incestuous enough for their taste (which happens frequently), you can now remind them that they are effectively reading a half sibling story.

 

[la_ruche]

Wow - some deep thoughts here!

 

[John_Vandermeer]

I have a half published (4 of 8 planned chapters) half sibling novella. Incidentally, in chapter one it is noted that genetically the main characters could be half siblings or double cousins. After the half sister relieves her uninformed (of their relationship) half brother of some of his cum, and sends it to the lab without his knowledge to make sure her theory is correct! The lab points out that detail in their report.

 

[TheLobster]

All those familial connections and genetics thereof are so complicated, I'm not surprised most characters in I/T stories keep it simple and stick to fucking their blood siblings and children.

 

[Kelliezgirl]

I used to work with a guy whose brother married his wife's identical twin sister.
I suppose that makes the cousins effectively 3/4 siblings.

 

[GlennJenko]

I haven't read a double first cousin Lit story, but I have done some research on it. I'm an aspiring historian and my passion is medieval kingship and nobility, so I'm familiar with there being a whole bunch of incest and the possibility of double first cousin incest and what that would mean genetically. Though I don't think I clocked that they'd have the same DNA as if they were half-siblings, even though it does make sense logically.