This is wild...and the design of the study is interesting too: "People who enroll in genetic studies are genetically predisposed to do so." https://arstechnica.com/science/2023/08/genetics-makes-some-people-more-likely-to-participate-in-genetic-studies/
Want to have your genes tested? It might be genetic

People in a genetic database have segments of DNA in common unexpectedly often.

Ars Technica