DNA and Genealogy

The 35th edition of the Carnival of Genealogy is being hosted by the Genetic Genealogist who is offering to analyze various genealogical mysteries which we think may be solved by DNA testing. The complete call for submissions is at the end of the 34th carnival.

As one who has had her brother's DNA tested in hopes of getting through a brick wall and instead of finding a common ancestor finding three more lines brickwalled in the same general location, I'm hesitant now to say that it is always going to be useful; however, I can see several things that might help us on researching that Thornton line if the right persons were tested. For example, we've always wondered if the David Thornton line of Fayette County, Alabama is related to the Richard Thornton line of Fayette and Walker Counties. If a male Thornton from David's line were to be tested, we would have a little more than similar naming patterns and an obvious economic disparity from which to make our observations. One researcher has tried to connect us with another group of Thorntons in the Tuscaloosa County area. This is a nearby county and certainly a good case could be made, but it is all circumstantial, and one can equally make a case against this scenario. The problem: I don't know a male Thornton who descends from these lines. All my contacts on these lines have been with females with other surnames and with whom I've lost contact because of e-mail address changes over the years. In the meantime, I'm working on documenting these other three lines back to the Carolinas where we are all stuck in hopes that I'll make a discovery that will get us past the brickwall.

I really am more intrigued right now with a mtDNA analysis. It's my understanding that this can tell you something about one's mother's mother's mother's mother and her ethnicity. This person for my mother (who is still living) would be Betsy Murry who is rumored to have Native American heritage. I can definitely place her husband in Indian lands in Georgia. My question for the Genetic Genealogist is whether I should convince my again mother to be tested or whether I could do the test. I would also want to know how likely I would be to determine that there is or is not Native American heritage in the matrilineal line with the mtDNA tests. There are different levels of mtDNA tests offered by Family Tree DNA. Which of these would be adequate to offer the information I desire and which would be best?