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This seems like it makes sense, at least within a certain retrograde framework. As the thinking goes, evolution might prefer babies who look like their dads, as maternity is clear while paternity is in doubt. In other words, if dads don’t know for sure that little ones are theirs, they won’t tend to them. But subsequent studies couldn’t replicate this result. “It's a very sexy result, it’s seductive, it’s what evolutionary psychology would predict—and I think it’s wrong," the psychologist Robert French, of the National Center for Scientific Research, in France, told Scientific American about the study.
Researchers stayed curious about this question. In 2004 Paola Bressan, a psychologist at the University of Padua, and Massimo Grassi, also of the University of Padua, tried again to get to the bottom of this question of familial resemblance, and found that children tend to resemble their parents equally, but the resemblance isn’t very strong. They theorized that this ambiguity might be advantageous if the paternity is unclear. “Men tend to invest more in children who (they believe) resemble them more; thus, children who look like their ‘social’ father—that is, like their mother’s husband—fare better than those who don’t,” Bressan told me. “The problem is that a child’s biological and social fathers are not necessarily the same person.”
Overall, “the evidence is slightly in favor [of babies looking like their dads],” says Steven Platek, an evolutionary psychologist who studies this topic. Platek thinks the data are distorted by unclear paternity, which he estimates occurs in 2 to 30 percent of births.
Scientists can only dream of perfect data. “An ideal [data set] would be random paternity tests on 10,000-plus father-infant pairs so we could know the going base rates of false paternity,” says Tony Volk, a developmental scientist who studies families at Brock University, in Canada. “But that hasn’t happened.” Researchers mostly find out cases of mistaken paternity by accident.
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Whatever the case, the researchers I spoke with seemed to agree on one point: The most clear-cut thing is not an actual resemblance, but that so many people perceive one. “Independent of whether the baby actually looks like Dad is the perception that the baby shares resemblance with Dad,” Platek told me.
Platek said I should be happy that seemingly everyone I know thinks my child looks like my husband. “When the perception and the reality match, the child treatment is the highest.” The father will freely make paternal investments in the child. Apparently when you think the child looks like you, even the diapers don’t smell as bad, Platek noted jokingly.
I chafed against this. It seems like we’re all self-deceptive idiots massaging the egos of fathers in an effort to get them to take care of their own children. (Interestingly, the mother’s family is one of the most common perpetrators of this effort. Platek told me research on families in hospital nurseries showed that the mother’s family members were the most likely to remark on how much the baby looked like the father.) It also felt regressive—that my husband would need our child to resemble him for him to get involved in parenting. Most important, I also have an ego and a face, and would like for people to tell me that my daughter resembles me.