Jack, you make a very good point about using surnames as the sole criteria.
My wife's maiden name is not Welsh although about half of her progenitors are Welsh coming from the Gwynn and Williams line. My own daughter's married name would not be recognized as Welsh even though she considers herself Welsh through and through. The Powell name willeventually disappear from our family tree because all of the "Powell boys" had daughters not sons. My own family tree contains the surnames of Powell, Lewis, Wynn, Evans, Gronow, Jones and Perry (at some point the spelling was changed from Parry to Perry). That said, I can't think of another method the reseacher could have used. I don't even think DNAwould be able totell much more than the broader classification of "European."
Personally, I refuse to answer offiicial questionnaireswheneverthey ask aboutrace: Caucasion, Hispanic, African, Asian and so on. If I am absolutely required to answer I check "Other"then write in "Homo Sapien." I believe that all humanity is of the same race. Many religionsand even modern day geneticists concur that the entire race is descended from one woman. Of course, there had to be a guy involved but geneticistshave only mitochondrial DNA to work with so far.