Let’s just get this out of the way: Yuck, and also yuck.
We acknowledge and understand the revulsion you may be feeling toward taking a dive into this topic, even if it is just Game of Thrones. But we had to know. So did you, apparently.
Let’s get right into it: Just how incestuous is Jon + Dany, according to science, law, and social mores?
In the case of pure human biology, it’s a pretty cut-and-dried case, though potential effects on offspring are poorly understood. As far as the law and social acceptance, well, depending on where you live, aunt-and-nephew sex ranges from totally not a big deal to … punishable by death.
That’s right, in certain parts of the world, Jon + Dany would be executed for their little pleasure cruise. Don’t even get me started on Cersei and Jaime.
But the truth is, Jon + Dany isn’t much better than their Lannister counterparts. Because this is Game of Thrones, after all.
First, the science
Biology defines inbreeding by “coefficient of relationship,” or the percentage of shared ancestry, ranging from 100% for identical twins (who can’t reproduce with one another, at least not until human cloning is a thing) down to 0% (or something very near it, presuming we’re all from the same primordial soup).
Points between on the relationship coefficient include:
Full siblings: 50%
Half siblings: 25%
First cousins: 12.5%
Second cousins: 3.13%
Third cousins: 0.78%
Fourth cousins: 0.20%
On a purely gross-out level, Jon + Dany as nephew and aunt is bad enough. But guys. It’s so much worse.
Multiple generations of inbreeding in the Targaryen line, where Jon + Dany are connected, would create a coefficient creeping up on 50% — brother-and-sister levels, by the math of one Redditor.
There may yet be hope for their unborn children, however
The actual effects of inbreeding in human populations — let alone individuals — is not easily quantified. It’s accepted that higher relationship coefficients increase the risk of recessive or deleterious traits showing up in offspring (including congenital birth defects), but the chances of that happening are not easy to pin down. They’re considered generally quite low on a case-by-case basis.
In other words, you can have a child with your niece/aunt (or sibling) and as far as we know, chances are pretty good that the kid will be healthy. Could also be a sadistic, murderous, beady-eyed boy-king with a punchable face, but odds are good that he’d be otherwise physically OK.
Scientific research (and countless generations of observation) gives us a somewhat better understanding of the effects of widespread inbreeding among populations, where manifestations can include reduced fertility, increased genetic disorders, poor facial symmetry, higher infant mortality and immune system dysfunction. Royal families are sickly and goofy-lookin’. It is known.
And in the animal kingdom, inbreeding ranges from risky/taboo (humans, domesticated animals) to not a huge problem (the banded mongoose, certain sea lion populations) down to downright normalized (fruit flies, which prefer to mate with siblings, with no known ill effects).
But let’s be clear here: No one thinks keeping it in the family is O.K. We’ve been wired to think incest is unnatural for more than one very good reason.
Which is why it’s against the law around the world
Most incest laws, both in the United States and abroad, prohibit relationships where the coefficient is 25% or higher. Sorry, Jon + Dany, but this new love is taboo in most of the world, and has been since before Biblical times.
Many of these laws are in place to prevent abuse of family power dynamics more than anything; penalties often become significantly more severe when one of the participants is younger than the age of consent. But most civilized places have penalties — including jail time and death — even when both parties are of age and willing.
Exceptions are few, far between and full of pitfalls. There are apparently no laws against incestuous relations of any kind between consenting adults in the Ivory Coast. Some places, like Argentina and Brazil, do not specifically criminalize incestuous acts but prohibit marriage between lineal relatives.
In the United Kingdom — the spiritual first-cousin of Westeros, let’s face it — sex with a 25% or higher coefficient relative is downright illegal, but how those offenses are prosecuted and punished depends on where in the kingdom you are.
Meanwhile in Zimbabwe, Vietnam and Iran, incest is a potentially capital offense, no matter how distantly you’re related.
And in the U.S., of course, state laws apply, and vary widely. Every state and the District of Columbia have incest prohibition laws, but some, like Rhode Island, only specifically prohibit marriage. The Jon + Dany-friendly state of Ohio’s laws only cover parents/children. New Jersey excuses anything when both parties are over 18. Some states (Nevada, Montana, Michigan) punish incest with up to life in prison, no matter the age/relationship.
What’s not to be done is done
America has had its share of high-profile borderline cases, from one of its presidents (Franklin D. Roosevelt, who married his once-removed fifth cousin Eleanor, too far apart to be much of a scandal) to Rock ‘n’ Roll pioneer Jerry Lee Lewis, who wed his 13-year-old first cousin (once removed) Myra Gale Brown when he was 23. That marriage, legal only via parental consent even in 1957, would last 13 years and produce two children. The scorn and scandal surrounding it, however, ended Lewis’ career.
And everyone knows the story of Woody Allen’s marriage to Soon-Yi Previn — which isn’t legally incest, but only on a technicality. Relationships with adoptive children are considered incestuous on the same level as lineal relatives in most societies; Allen was never legally a parent to Previn, who was adopted by Mia Farrow and her previous husband, André Previn. But his place as a father figure before their relationship was publicized when she was 19, and details of how it all developed, would never sit right — especially after new sexual abuse allegations emerged years later.
More recently (and on a lighter note, to conclude this altogether unpleasant inquiry) researchers in Souther California are celebrating the arrival of two endangered puma cubs in the wilds of the Santa Monica mountains, named “P-59” and “P-60.” They are also concerned about the puma population at large, due to a scarcity of big cats in the area: The cubs’ father is suspected to be “P-12,” which would also make him their grandfather, great grandfather and great-great grandfather.
Wow, P-12. You make the Lannisters look downright pure. Such a thing would never happen in King’s Landing, though we can’t speak for that savage north of The Wall.
This is Game of Thrones after all.