The art of mating has undergone many technologically induced changes from the liberation that young lovers found with the invention of the automobile to the swipe-right ease of matching on Tinder.
But another technology is afoot that few people know about but that will upend the way we match and reproduce in years to come: the polygenic score. This is a single number that sums up someone’s genetic potential—risk for disease such as diabetes or predicted height or even the genetic portion of her IQ.
With the spread of recreational genotyping through services like ancestry.com or 23andme, more and more Americans have learned some of what their DNA can tell them about their past (their ancestral origins) and their future, such as their risk for diseases like Alzheimer’s.
What does all this have to do with dating and mating? Well, now that a computer app can take the raw data of our Cs and Gs and Ts and As and spit out a single number—the polygenic score—that predicts (with error, of course) someone’s height or risk for cognitive decline, would you like to know whether the person who just proposed to you is a walking genetic time bomb?
We have always selected our mates for their phenotypes—outwardly observable characteristics—that are driven partly by genetics and partly by environment. Now that we can somewhat measure their genotypes—the actual stuff that a baby daddy passes on to junior—it is inevitable that discerning potential partners will demand their counterparts show their cards before committing. Even if you landed a man or woman with advanced degrees, would it give you pause if you learned that he or she was genetically likely to develop early dementia and, worse, pass that risk onto your offspring?
In research I have performed with colleagues, we find that we tend to match on observable traits like education and body-mass index, as we have to a degree for time eternal. That is, we are more likely to marry someone similar to us in these outward dimensions than if we hooked up by chance. We are doing this on a genetic level, too, as a byproduct of how we sort on health, social status and so on.
There has been lots of big talk lately about the gene editing technology known as CRISPR. This allows scientists to swap out undesirable DNA for a custom-designed replacement sequence. While it holds great promise for addressing single gene diseases—think Huntington’s—it is probably less useful for addressing traits that are highly polygenic—meaning that the outcome is determined by myriad tiny effects spread across the entire genome.
In five years, sperm and egg registries are likely to offer extensive genetic profiles along with the photos and descriptions of donor hobbies they now provide.
In 25 years, dating and mating are likely to look very little like they do today. Computer algorithms that calculate our genetic potential and sort potential mates like a medical-school match are likely to be the new yenta-bots.
We need to be careful as we step into this brave new world of reproduction: After all, phenotypes are for fun (i.e. hookups) but genotypes are forever.