Kitty Geoghan is the Photo Editor for Hatter Network

Although it’s not the most pressing science news out there today, for my first real Skeptical Science Sundays column, I’d like to talk about one of the first science news items I ever publicly criticized. Posted on the Your News Wire website (hardly a verifiable science news source), an article boasted the title “Women Absorb And Retain DNA From Every Man They’ve Ever Had Sex With,” paired with a terrifying photo of a woman looking like she’d just made a fatal mistake. If you’d like to read the article yourself, I invite you to do so, and then flip back here to see exactly what’s wrong with this kind of reporting.

So, to start, let’s look at the study being addressed. There are two, actually: one by Chan and colleagues titled “Male Microchimerism in the Female Brain,” and a follow-up by Yan and colleagues titled “Male Microchimerism in Women without Sons.” Taken together, these studies looked at a phenomenon called microchimerism, in which living, genetically distinct cells from one organism are present in another. In particular, they found cells in female brains that contained a Y chromosome, indicating that they came from a male organism. Approximately 63% of the women in the first study exhibited this phenomenon. The researchers suspected that the cells were a result of pregnancy with a male child, but in the second study, only women with no sons were studied, and 21% still exhibited microchimerism in the brain.

These studies are incredibly new, have not been replicated, and represent a phenomenon that researchers currently know very little about. All of these factors should inspire skepticism, and in the researchers, they did: The second study made no direct claims about conclusions of their research. Instead, they presented a list of avenues for further research, as is commonplace in science. Among their suggestions for possible origins of the phenomenon were “unrecognized spontaneous abortion, vanished male twin, an older brother transferred by the maternal circulation, or sexual intercourse.”

According to Your News Wire, however, this explanation was not good enough. Clearly these scientists must be hiding something. Why else would they make their results so ambiguous? It can’t possibly be because their research is new and has yet to be replicated further – no, clearly they’re masking the truth to promote their political agenda. The REAL reason male microchimerism exists, according to Baxter Dmitry, is exclusively because of sex.

While it’s true that sexual intercourse was proposed as a possible origin of the male microchimerism phenomenon, it was not a variable studied by any of the researchers. In fact, it was last on their list of possible explanations, and has yet to be even considered for further study. But none of that matters to Dmitry. To him, the answer was clear. These researchers were “living in denial,” desperately attempting to cover up the truth: that the DNA of each of a woman’s past sexual partners is forever a part of her, to the point of fundamentally altering her brain chemistry. Keep your legs together, ladies, because that one night stand is going to affect you for the rest of your life.

Of course, this is all a load of bull. For one thing, the article doesn’t even acknowledge the distinction between the two studies when making its bold claims. The first study found microchimerism in 63% of its sample, which is admittedly a rate too high to be explained by most of the proposed hypotheses – but in this study, much of that percentage was explained by the women having given birth to sons. The second study, which looked only at women with no sons, found that only 21% exhibited male microchimerism, and that’s the study that suggested other possible explanations. One of those possibilities offhandedly dismissed by Dmitry was “unrecognized spontaneous abortion,” which refers to a miscarriage early enough in the pregnancy that the mother didn’t even realize she was pregnant, not “an abortion the woman didn’t know about.” (Honestly, if you don’t even know what a “spontaneous abortion” is, you probably shouldn’t be writing about science in the first place, but I digress.) Considering the likelihood of miscarriage early in a pregnancy, it’s not entirely impossible that those 21% of women had actually been pregnant with a son and not known about it.

Another explanation is that when a mother has a son, develops male microchimerism herself, and then becomes pregnant with a female child, that child will inherit the male brain cells from her mother. This could also explain that 21% figure – it’s not unreasonable to think that 21% of the sample had older brothers. However, since this was a post-hoc hypothesis suggested after the study, no data was collected on these particular women’s family structures, and this possibility could not be explored. This is precisely why the study calls for further research to gather the data they were missing.

In conclusion: ladies, don’t panic. The odds that the DNA of every college hookup is forever sealed into your brain are incredibly low. And anyway, even if sex is to blame for this phenomenon, there is no indication in any of the research so far that male microchimerism has any significant effect on women’s brains, whether negative or not. The Your News Wire account is nothing more than horribly inaccurate fear-mongering meant to convince women that sex is evil. While male microchimerism is certainly an intriguing phenomenon, it’s hardly the groundbreaking discovery that Mr. Dmitry would like it to be.