This definitely concerns me – in my opinion, the chance of detecting non-paternal events is one of the true ‘social’ concerns of genetic genealogy. As a result, I think students should be able to opt out of an experiment if they or their parents object. Perhaps they could substitute someone else’s DNA, such as a more distant family member.

However, I would posit that although there is surely a chance of there BEING a non-parental event in a large group of students, the chance of CONCLUDING that there was a non-parental event is quite small. Most genetic genealogy companies return a list of allele numbers (12 alleles for the Genographic Project) for Y-DNA or a list of mutations for mtDNA along with a probable haplogroup designation. Armed with that knowledge, how is a student going to determine that there was a non-parental event?

For instance, with mtDNA, unless the student is planning to compare that with a relative in the female line, there is virtually no chance that the results will support a non-parental accusation. Even if the haplogroup is far different from what was predicted, that certainly does not suggest that there was a recent non-parental event.

The same is essentially true for Y-DNA. The student would have to compare this information with closely-related individuals to conclude that there was a non-paternal event. A wildly unusual haplogroup designation does not automatically suggest that there was a recent non-paternal event.

As a final caveat, I would add that the growing popularity of genetic genealogy and subsequent public databases does increase the likelihood of these types of problems. However, there are still so few people who have been tested (600,000 to 700,000, by my estimate), that the chance of finding (1) a close hit, and (2) a close hit that supports the finding of a non-parental event, is very very small.

Note: I used the term “non-parental” event to include an event of non-parentage on either the male or female line.

This information is likely to come out during genetic testing. It’s one of the classic cases of an ethical dilemma. Does this concern you? You will be pressuring students to go ahead with the testing even though their mother might object.