I figured I'd be 60% English, only like 10% though. Interesting as all heck, everybody should spend the 99 bucks and spit in the tube. I also was 20% Irish, 5% Iberian (DNA from the Romans who also invaded England) and 2% Greek; imagine that. No Afri though, ha ha; wouldn't claim it if I was anyway.
My wifey is waiting on her DNA to come back. Once and for all we will know for sure she is Polish and not Slovak; something I've known my entire life.
I know where my father's ancestors were living for hundreds of years. My mother's mother was third-generation American (3 German immigrant grandparents and 1 Irish immigrant grandmother). My mother's father had English, Scots-Irish, and maybe some Pennsylvania German ancestry. So I don't know if I would learn anything I don't already know by having the test done.
It costs less than $100 (perhaps plus shipping) to have your DNA tested by any of the big three American genetic testing companies, (Ancestry.com, 23and Me, and FamilyTreeDNA). However, many people who have been tested by more than one company have found their “ethnic heritage” predictions vary greatly. It is NOT an exact science. Part of the variation is attributable to ancestors moving around – your ancestral line may have been in Rome 2000 years ago, then in Saxony 1500 years ago, and in what is now Germany 1000 years ago prior to moving to England and finally to the US.
Those could also be the ancient Iberians, who with similar groups inhabited Europe before the Germans or Romans or Celts came on the scene.
It's certainly possible that the ancient pre-Celts who got pushed down into Spain by subsequent arrivals and those who were pushed into Ireland or Wales or Scotland had similar DNA.