I've actually had a lot of fun with this very topic since I took the Ancestry DNA test and my husband bought me the ridiculously advanced subscription to do a family tree.
I'm from northern Michigan, and my family is all still there. My mom's side is 75% or so French Canadian. I can trace my Grandma's mom's side on several different branches back to the King's daughters. The other side is 3rd generation American/English. On my mom's dad's side there's again, French Canadian (able to trace at least one line back to the King's daughters), the other side is traced back to Salem, MA in 1650, originally from England. We have several of that branch to serve in the Revolutionary war. Throw in some Irish, a Scot or 2, a German, supposedly an American Indian or 2 and a Spaniard and that's my mom.
My dad's side - his dad was 1st generation American. His dad was left at a train station in Poland in 1885 when he was 8 and was taken to Germany to work on a German farm after being abandoned. He immigrated to America in 1906 to work in the Boston textile mills, where he met his wife, who had also just immigrated from Poland. I can't get very far back with them.
My Grandma on my dad's side seems to be English, Irish and a smidge of German on her dad's side, able to trace them back to the 1750's. His mom's side I can trace several branches back to 1630's New York when it was settled by the Dutch. There seems to be some Scottish,French and Germans in that branch as well, but lots and lots of Dutch.
My DNA? Reflects very little of the French, even though the French Canadians as Catholics kept immaculate records and it's easy for me to obviously trace branch after branch.
Instead, I'm showing up as very German in my DNA, even though very little of my family was from Germany. However, many of my French relatives can be traced back to cities that border Germany now, and I guess it's common for the bloodlines in Western Europe to be intermingled due to fluctuating borders throughout the past millennium. I'm very English, Irish and Scot with only 11% Eastern European even though my Grandpa was 1st generation American.
It's been fun to trace all of these several hundred lines back as far as paperwork will allow, with lots of surprises along the way. Lots of work, and sucks you in. Hours and hours and hours - I told my husband I won't renew my membership until late fall. I enjoy summer too much to spend it indoors on research, regardless of how interesting or enjoyable I find it.