The holiday season means presents galore — but in the case of at-home DNA tests, some gifts may be better left unopened.

As experts told USA Today, the prevalence of self-serve DNA testing has made it much more likely that people discover painful family secrets — for instance, that one or both of your parents are not your genetic relatives — upon getting their results.

For years now, we’ve come across reports about people learning of their parents’ affairs via DNA testing kits from companies like Ancestry or 23andme.