Ever make bug because you wrote code thinking about how you wanted it to work and forgot to consider how it could go wrong off of that happy path? I think things like this are basically the same problem: when someone is focused on the good outcome it’s just not the right context for most people to carefully evaluate possible negative events, especially low-probability ones. They’re thinking it’d be cool to get an ancestry report, maybe lifesaving to get notice of genetic problem, perhaps the excitement of a unknown relative, and unless there’s a neutral party involved the positives are probably going to win.