Is it OK to sleep with your cousin? It depends on what you mean by “OK” and “cousin”—as well as whom you’re asking. According to Senate candidate, TV doctor, and actually pretty good heart surgeon Mehmet Oz: “If you’re more than a first cousin away, it’s not a big problem.”
Jezebel reported the existence of this doctorly advice on Tuesday. It comes from a 2014 morning radio appearance, in which Oz weighed in on a question from a listener. Specifically, the host asked Oz if it would be “safe” to “smash” one’s cousin; Dr. Oz replied yes, with the big caveat that it not be one’s first cousin. Digging a bit deeper into the biology of incest, he bantered about how his own daughters aren’t attracted to him because of how he smells. (Awkward? Yes. Scientific? There’s been a study.) To all this, Jezebel’s Caitlin Cruz wrote: “I just … I just don’t know what made this man think he should run for office.”
I don’t know either! The man may be a huckster, a jaw-droppingly error-prone candidate, and, as his opponent for one of Pennsylvania’s Senate seats has reminded us many times, a New Jersey resident. Truly, Oz should go back to the operating room or forge a new life sitting around with his TV riches, and give up the pretense that he is in any way fit to be a senator. But I have to say: I don’t think saying that it is “OK” to sleep with your second cousins should disqualify you from running for office. In fact, in this instance, I think Oz was right.
It’s worth explaining first why sleeping with cousins would be “bad.” For this, let’s take one of the world’s most famous cousin-sleep-withers, a total deadbeat know-nothing named Charles Darwin. Along with the theory of evolution, the man fathered 10 kids with his first-cousin-slash-wife, Emma Wedgewood. This was a pretty normal thing to do during Darwin’s time, the 1800s. “People didn’t travel far to find a spouse, and the closer you were to home, the more likely it was you’d marry within your family,” wrote Steph Yin in 2018 in the New York Times, reporting on a study that suggests that after 1875 in Europe and North America, “partners started to become less and less related.” It helped that railroad travel had recently become a thing, and people could venture further into the world to live and date.
Darwin’s offspring illustrate why moving away from cousin marriage was an adaptive social trend: Only seven of his kids made it to adulthood, with one of them living just 23 days. In 2010, researchers at the Ohio State University scoured family trees and calculated Darwin and Wedgewood’s “inbreeding coefficient.” Yes, it was easier to die in the 1800s. But the study concluded that the couple’s similar genetics could have played a role. If you have two parents who share a grandparent, the likelihood that they’ll each give you a gene that, say, makes you less capable of fighting off an infectious disease is higher than it would be otherwise. (To be specific, when first cousins have kids, the risk of genetic disorders roughly doubles, though the exact risk will vary from couple to couple. In cousin-cousin couples, it’s still just a few percent.) Even when it comes to Darwin’s kinda-inbred kids, “it’s not all genetic doom and gloom,” said Tim Berra, the 2010 study’s author, in a press release. “Three of his sons were so prominent that they were knighted by Queen Victoria for their achievements.”
Marrying your cousin is outlawed in many—though not most— U.S. states. In some places where it is legal, there are restrictions; for example, Maine requires couples to get genetic counseling first. And only a few states outlaw sexual relations between cousins. (Pennsylvania, for what it’s worth, is not one of those states.) And outside of America, Oz wouldn’t even be breaking a taboo with his statement. “There’s so much stigma about this whole topic, and in many parts of the world it’s common for cousins to marry,” said Robin Bennett, a genetic counselor and professor at the University of Washington Medical Center. In fact, “one billion people worldwide live in countries where marriage among relatives is common,” wrote journalist Martina Merten in a 2019 piece in The BMJ, a medical publication, noting that it’s particularly common in Pakistan.
The practice has its advantages, Merten’s sources told her, from keeping wealth in the family to already knowing your in-laws. The “solution” to the genetic pitfalls that can result from such relationships isn’t shaming, or even making these marriages taboo. Offering genetic testing, in particular less expensive testing, Merten and others suggest, could help prospective parents work out if they’re at risk for each passing on genes to their kids that could leave them with a disorder like cystic fibrosis. In the U.S., “most couples are screened for those disorders no matter who they’re having a child with,” says Bennett. It is not the 1800s; as with so many other aspects of procreating, the technology is available to navigate this.
So, having kids with your cousin—potentially not so bad, strictly from a genetic health perspective, and maybe even socially healthy, depending on where you live exactly. And second cousins? The “risks are not much bigger than for people who are not closely related,” says Bennett. In general, “the chance that a baby is born with a birth defect or disability is between 2-3 percent,” wrote genetic counselor Rebecca Luiten in a 2015 blog post for The Tech Interactive’s “ask a geneticist” series. “At 3.5 percent, the risk is slightly higher for second cousins.” (The Tech Interactive is, for your information, “a family-friendly science and technology center in the heart of downtown San Jose.”) All of which should make having a romantic relationship with your second cousin, scientifically speaking, not that scandalous.
And Dr. Oz wasn’t even giving a green light for bearing offspring—the (slightly) risky part! Just “smashing.” Which in many cases—like two same-sex partners or with one partner who has gone through menopause—can’t even result in kids. It’s not like he discouraged contraception!
In fairness, Cruz ultimately describes Oz’s cousin comments as “fine…benign even,” honing in on the line about pheromones and families as the icky part. But the framing of the piece around “smashing” and “cousins” is undeniably shame-y. And it’s not Oz who is really hurt by the stigma, it’s folks from parts of the world where this family structure is common.
There are plenty of reasons that Dr. Oz should not be the junior Senator from Pennsylvania. (Including, while we’re on the topic of sex, that he has said he thinks life starts at conception and that abortion is murder.) But the cousin thing isn’t one of them. I can’t help but think if “go ahead, have sex with your second cousin” came out of a Democrat’s mouth, the right-wing media would be all over it. And Jezebel? It just might run a headline defending them.