"Your Baby Looks Like Your Ex—Shocking New Research Shows Previous Partners' Sperm May Lurk Inside You."

Catchy headline, right? When you write about science on the Internet, that's really the key. Last week, dozens of media outlets took this "shocking" tactic in blurbing a new study on fruit fly reproduction, the research written up with headlines about lovers and accompanied by photographs of bouncing human babies. I even received an email from a pregnant friend that read, "Shit. Does this mean my kid is going to look like my ex?"

I wrote back to her, "Not unless you're a fruit fly."

How did we get from Telostylinus angusticollis to the human infant? Start with a scientific study that can be generalized to something people identify with or fear. Then lead with an eminently clickable headline about motherhood and promiscuity, striking fear in the hearts of the sexually active, raising concerns that the skeevy dude they picked up in a bar last year is actually going to haunt them forever through the face of their future offspring. Make a subtle but technically correct change in the wording of a study by anthropomorphizing female flies and their offspring as mothers and babies. Spend a few sentences referencing the science and then speculate on what this means for readers. Hit publish.

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One of the first rules you learn as a researcher is to read the source material. So let's talk about the actual findings published in Ecology Letters. The study's authors (Crean, Kopps, and Bonduriansky) hypothesized that characteristics of previous mates could influence female flies' future offspring, specifically their size.

To test this, the researchers first grew male flies of variable body size by placing larva on either a nutrient-rich or nutrient-poor media. Female flies with immature ovules were mated with either the large-bodied or small-bodied male flies. They were then paired with a fresh set of mates and the offspring were studied by researchers.

To understand the process, you need to know a bit about the reproductive development of female fruit flies. (I know, exciting! You can see why this study was so widely publicized internationally.) The immature eggs of newly hatched fruit flies ultimately develop a hard shell. The thought is that the development of the immature eggs can be influenced by non-genetic factors in semen but, once they have matured, the eggs are no longer susceptible to these changes.

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The results were consistent with researchers' hypothesis: the body size of the offspring matched the size of the female fly's first mate rather than the genetic father of the offspring. It seems fly semen of a prior partner has the ability to influence egg development and have non-genetic paternal effects: in this case, determining body size. If you're interested in either fruit flies or insect genetics, this is a fascinating discovery.

But of course, the study never mentions humans. Why would it mention humans? The research is about flies, a species with a vastly different reproductive anatomy and cycle than mammals. That taxonomical leap was made entirely on the part of the media.

Because the average reader is not going to click on an article about the effects of fruit fly semen, but certainly would click on a headline speculating that prior sexual partners might determine the appearance of your future offspring. Here is what happens when we put this science article about fruit flies into the media science cycle:

Scientists Say There's A Chance Your Baby Could Look Like Your Ex

According to the Telegraph, the size of a studied group of newborns was determined by the mother's first sexual partner, rather than he who was actually the biological partner.

Old Lovers and Genetics: Babies Can Inherit Traits of Mother's Old Flame

Offspring could take after mother's ex-lover

Could previous lovers influence appearance of future children?

My personal favorite was accompanied by a photograph of Brad Pitt and Jennifer Aniston with the caption "Exes Jennifer Aniston with husband Brad Pitt never had any children but what's to say his current brood don't look a little like her?" If you're already switching the species of the original study, why not reverse the genders as well?

The fruit fly study is only one of hundreds of cases in which science filtered through the popular media fails to provide accurate information, and leaves traces of misinformation behind. A particularly amusing example was when a study about the protective effects of hydrogen sulfide went viral under headlines about the mythological healing powers of farts. Other instances have had far more catastrophic effects. The anti-vaccine movement can be traced in part to the media trumpeting the falsehoods of Dr. Andrew Wakefield in an astounding failure of critical science reporting.

Many readers assume that the science and health articles they consume on the internet and in the newspaper are carefully vetted. But many science pieces in popular media take for granted that a study published in a scientific journal is unimpeachable. We are reading articles written about other articles, written about press releases: before you send out a deluge of panicked emails about an ex's sperm, keep that in mind.

Image by Jim Cooke, photo via Shutterstock.

Caroline Weinberg is a doctor with a masters in public health and a background in international healthcare. She is committed to health education and thinks it's time the media starts accurately reporting on science and health. She also apologizes for using a sensationalized headline to get you to read this article.