I have done some family tree work. My mums paternal line I have got back to mid 17th century in St Austell (cornwall) they pretty much stayed there. At one stage they moved all of 10 miles away , had my great grand father been born first I would probably have been a farmer as thy are still there. My GGgrandfather went back to St Austell to the clay mines.
My fathers side is Belfast and I got back to 1840s but can't get back further at this point as records are thin on the ground due to their destruction in two fires. It would appear he my GGgrandfather came from north of Belfast. What is strange is he was catholic and where he came from was very predominantly protestant so wondered if he arrived there from England / Scotland his family name is not Irish and pretty much all the boys names were English. So I guess I was wondering what a DNA test might tell and the accuracy of such.
Cheers for the help.
The Ancestry DNA test will give you some cousins with common ancestors going back about five generations, so I get some useful results re the early 1800's. But matching that far back does get patchy, because each generation is halved. Cousins can have useful information, especially if they still live in the same area as your ancestors.
You'll also get general ethnicity estimates, but they probably won't tell you an awful lot. A Y-DNA test might give you some matches for your father's father's father's father's father's father's father's father, etc, but disappointingly few people pay for that.
PS. I wouldn't advise using other DNA companies - they have much small databases than Ancestry, and anyway you can copy your Ancestry data to all of them (free or cheap) except 23andMe.