Everyone tells me I look just like my dad. Brown eyes, bushy eyebrows, square head, cleft chin and hair feathered like Elvis. We walk with the same unassuming trot, we don’t smile in pictures and when we speak passionately a trident-shaped vein bulges in our right temple.
Depending on my dad’s recent diet situation (sometimes it’s paleo; sometimes, whiskey and potato chips), I accept the comparison with varying degrees of pleasure. While I respect and love my dad—and admire his hairline—I don’t want to be him.
Do I have any choice in the matter, though? Or is his DNA my destiny? What does the science of paternal genetics have to say about my lingering fear of repeating his mistakes, winding up with his health problems or registering as a Republican?
As it turns out: not much.
“You’re going to find it very difficult to construct a story around traits that you inherit solely from the paternal line,” said Dr. Scott Bultman, a geneticist at the University of North Carolina whose colleagues recently discovered that, though we inherit an equal number of genetic mutations from each parent, we use more of the DNA that we inherit from our dads.
Speaking with more experts revealed few more answers. I counted off a list of traits, from hair color and jaw structure to intelligence and temperament, to no avail. I even asked a Ph.D. candidate about whether or not penis size is linked to the paternal line. She was unamused, but she did offer that erectile dysfunction can be hereditary (just not necessarily via dad’s DNA).
The researchers I interviewed all agreed that—while there is research that suggests some mutations have different consequences depending on whether the genetic variant is inherited from the mother or father—there’s no scientific evidence that links any specific trait to one parent over the other. There is also no rush to figure that out, Bultman said. “Most of the research in genetics is more concerned with understanding and identifying hereditary diseases so that we can help eliminate them.”
Color blindness, which occurs on the X chromosome, is one mutation where gender makes a big difference. “Since men only have one X chromosome they are more likely to be affected by the condition,” says Sha Sun, a geneticist at the University of California at Irvine. Bultman also mentioned Prader-Willi syndrome, a genetic disorder “in which several genes on the paternal chromosome are deleted or unexpressed, which causes obesity, intellectual disability and shortness in height.”
At this point I realized it was time to pursue the father-son connection in a different field. Namely epigenetics, an emerging discipline concerned with how a parent’s environment and the decisions they made before having children can affect the child’s development. If that sounds sketchy, that’s because by most scientists’ standards, it is. “The majority of the evidence stems from tests done on mice and is extrapolated to the human genome,” says Shannon Rego, a genetic counselor at Stanford University. But what epigenetics lacks in scientific certainty (if there is such a thing) it makes up for in quixotic aphorisms.
In a study conducted at the University of Copenhagen, scientists found that male rats on a high-fat diet fathered offspring that tended to gain more weight, develop more fat and have more trouble regulating insulin levels compared to the offspring of rats fed a balanced diet. In another study, researchers dug up records from the Swedish municipality of Överkalix going back to 1799. Counterintuitively, they found that when boys between the ages of 9 and 12 ate badly during the years right before puberty, their sons, as adults, had lower-than-normal rates of heart disease. When boys ate well during that period, their grandsons had higher rates of diabetes.
Epigenetically speaking, there is even evidence that links traumatic experiences to inheritable traits in offspring, meaning that it’s not impossible that my father’s paintball-related near-death experience early in his life may have in some way shaped my cognitive development. But the science behind that idea is about as reliable as Elon Musk’s theory that “we’re all probably living in a simulation.”
With epigenetics in my arsenal, my search for a certain father-son connection seemed to move farther from science and closer to science fiction. One obscured study suggested that mice could inherit their father’s trauma to such a degree that they would become depressed and refuse to drink sugar water. Another paper found that fathers who smoked between the ages of 9 and 11 sired sons that had a higher chance of becoming obese. The findings were interesting, but increasingly felt like cryptic anecdotes about the ways my dad could have accidentally voodooed my development. It appeared that scientists too, were grasping for any information that could help build a case for or against my DNA destiny.
“Inherent in science—we have no truths, and in the case of genetics our theories are constantly evolving,” Dr. Amos Landgraf, a geneticist at the University of Missouri, told me near the end of my search. But I had already figured that out.
Andrew Fiouzi is MEL’s editorial assistant. He last wrote about Five High-Tech Ways to Protect Us From Tech.
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Andrew Fiouzi
Andrew Fiouzi is a staff writer at MEL.
