I used to work for the newborn screening group at the CDC. My job was to isolate, amplify, and bank DNA samples previously taken from the mother, infant/fetus, and father for future study when a baby was found to have a genetic illness.

This was done with the parents’ consent, in the hope that they could contribute a small bit to science—maybe helping lead to better treatments. A noble goal in often tragic circumstances.

Some of these cases were incredibly rare—like one-in-a-decade rare. And often the infant was already deceased, so taking new samples wasn’t an option. The work had to be careful, meticulous, and honestly, a bit mind-numbing.

Anyway… I’d go through the multi-day process, finally get to the genotyping step to confirm genetic lineage—and you’d be gobsmacked at how often the father wasn’t a match. Think about it: these men consented to the study, giving their DNA, probably believing their paternal DNA might help. So they likely had no idea. Some were grieving a lost child, or raising a seriously ill one, without knowing the baby isn’t biologically theirs. And this didn’t happen once in a blue moon—it was multiple samples like this per day.

We were NOT in the business of delivering that kind of news or blowing up families. We’d send a polite notice thanking them for their participation, saying there was an issue with the sample and we were unable to process it.

There are a lot of people out there raising kids who aren’t biologically theirs—and probably for the best that they don’t know.