Can DNA solve these mysteries?

For the 35th edition of the Carnival of Genealogy, The Genetic Genealogist, who has a Ph.D. in biochemistry with a concentration in genetics, has offered to analyze whether or not certain family mysteries could be solved by DNA tests.

I’d actually been giving this some thought prior to the announcement, reading various websites, wondering whether I should get a test done, or convince a relative or two to do so. A relative has already participated in the National Geographic Genographic study, which might eliminate the need for others in the family to take the same/similar test.

There are basically two mysteries/questions. My non-expert conclusion is that DNA could help solve one of them, but unfortunately, not likely the other.

Family Mystery #1

There is a family myth that we have a Native American ancestor. My mother’s mother’s mother’s mother – Sarah Hartley, who married Ebenezer Denyer. (If true, it is significant, since Ebenezer's brother, Samuel, was killed by Native Americans, as his daughter, Ida, wrote about in her poem. The 1870 census indicates that once both her parents had died, Ida spent some time living with her uncle, and possibly Native American aunt. There may have been some tension there if her ancestry was known.)

No vital statistics are known about Sarah (birth date/location; death date/location; names of parents) so tracing her ancestry is difficult by normal means. If she were a full-blooded Native American, or if half-blooded, and her mother was full-blooded, it is my understanding that an mtDNA test of either myself, or my mother, would verify this. Of course, if the test came back negative, it would still be possible she was half-blooded, and her father was the full-blood.

There are some reports of genetic tests that tell you that you are x% Native American. That suggests that it isn't telling you about your mother's mother's mother's mother's.....mother only. That it can look at your broader genetic makeup. If that is possible, then it's likely my mother should take the test, because whatever the percentage is, her percentage would be twice mine, and easier to detect.

Family Mystery #2

This mystery is whether or not my research regarding Selig (Dudelsack) Feinstein’s siblings is correct. I think I have found one brother (Julius Odelson) and one sister (Tillie Oberman). Unfortunately, no descendants of the sister would have the Dudelsack Y chromosome. I wouldn’t either, but there are several direct male descendents of Selig who might be willing to take the test. Possible brother, Julius, had two sons, though I believe only one had a child, and that child was a daughter. So even if she has living descendants (which isn’t clear) there’d be no way to test their relationship.

So I’m left with Tillie’s death certificate, with parent names that match Selig’s, which is almost certain proof in my mind that she was Selig’s sister, and by deduction, the likelihood that Julius was probably their brother. Julius had a daughter who probably has some descendants in St. Louis, but the name of her husband was relatively common, and the list of people I’d have to blindly write letters to is extensive. I might do it, but it’s not a job for DNA.