I didn't immediately understand the point you're making there because I don't think you'd ever need to use Wikipedia or a list of sex offenders as a source, but I think I see your point now: if for 98% of people the specified source is a government register of births then anyone who doesn't have that source mentioned will stick out and an astute reader will immediately infer that they were born in a place where the register of births is not easily accessible or they have changed their name or something like that. So mentioning the sources is, as you say, a tricky issue.