I know Smith & Teall's "Tartan for Me!" lists various Scottish, Irish, Scots-Irish, etc. surnames and appropriate tartans, and I believe they determine which tartans by areas where large numbers of people with that particular surname live -- Matt, you want to help me on this?

However, if you know your ancestry to be Welsh, then a Welsh tartan, like the Welsh National, might be more meaningful, but certainly not "required" or your only choice.

T.