Here's my understanding of the differences between the two tests in a nutshell (if you can put understanding in a nutshell ;-). The Y-DNA (male line) test will give you a halogroup but is most valued for it's ability to prove or disprove a genetic match with another male with the same surname. So it could potentially give you more specific information about being related to someone say 5 generations back or less. From the DNA Heritage web site:
Y-DNA testing is at its most powerful when used with the existing paper records in trying to prove (or disprove) a theory or connection between two males with the same or similar surname. This can also be expanded to compare many males with the same surname as part of a Surname Project.
The mtDNA test (female line), on the other hand, assigns you to a halogroup and gives you theoretical information about the migratory patterns of ancestors who lived thousands of years ago. From the DNA Heritage web site:
I can have my own mtDNA tested, there's no debate there. Because I'm a female I can't participate in a surname study with my own DNA, it's only done with a male's DNA. So then I must consider which male, if any, would I want to ask for a DNA sample for a Y-DNA test.
After giving this considerable thought, I came to the conclusion that there are only 2 male lines that I could pursue from a practical standpoint (because I don't know donors to ask for the others). One would be my father's line. I have two brothers and I'm pretty confident that I could persuade one or the other of them to donate their DNA if I really put my mind to it. Neither one of them has more than a polite interest in genealogy but either would probably cooperate if I made a solid case why they should. Making the case would be ever so much easier if there was someone else who I was trying to prove a relationship to. But there isn't. I think I would have a difficult time trying to make the case that there may be someone's DNA already in a database somewhere or someone's DNA may appear in a database sometime in the future that would come up as a match and then we would know that we are related to them but not necessarily how. To an avid genealogy fan, this doesn't sound like such a bad deal but I'm thinking my brothers would come back with, "you're kidding, right?" I have to admit, it isn't a compelling argument even to me.
The other line that I could pursue would be my maternal grandfather's line. I could ask my mother's brother to donate a sample of his DNA. To be honest, this line is much more interesting to me than my father's line and would be my "line of choice" to pursue if all else were equal. I have no idea how my uncle would feel about donating a sample of his DNA. We're not close, I understand he's showing symptoms of Alzheimer's disease (it runs in the family), and he's very hard of hearing. Trying to explain all this to him would be challenging to say the least. Again, it would be much easier to make the case if I could just say, "I think that person X might be related to us but I need a sample of your DNA to know for sure". But of course there is no "person X" so I can't say that. My maternal grandfather had two "cousins" who came to America that I haven't actually been able to establish a family connection with. It would be nice if a DNA test could establish that. The problem is, they don't have the same surname so they would be related to my grandfather through their mothers not their fathers. It's highly unlikely that their DNA would be a match with my uncle's.
If I were a male there would be no debate. I would have the Y-DNA test done and hope that a match comes up with someone at some point and be content with just learning my halogroup for now. (I've already determined that there are currently no surname studies being done on any of my eight great grandparents' surnames.)
If I had the DNA results of someone I thought might be a relative or someone suspect who was also willing to give a sample for a Y-DNA test, I would put forth the effort to explain it to my brothers or my uncle in an effort to establish a family connection. If there was a surname study being done that would be a compelling reason to pursue it too. But I don't think I'm willing to try to make that explanation and put them on the spot just to learn our halogroup.
In the early days of the telephone there weren't many people you could call. You were limited to only calling up the few other individuals who were inclined to have one of those contraptions. Over time, more and more people got telephones and the pool of people you could call up increased dramatically. Nowadays, almost everyone has a telephone. You could call up millions of people if you were so inclined. That's a good analogy to the current situation with Y-DNA genetic genealogy tests. Right now, relatively speaking, there aren't all that many names/results to compare your DNA with. But I believe in the future it will be commonplace for people to have these sorts of DNA tests done. The databases will be much larger, as will surname projects, and matches will be usual and expected. But the field isn't there yet. It will take time to get there and I think the biggest factor influencing the time is the cost of the tests. If you could have a test done for $19.99 instead of $100-$250, you'd see a lot more people signing up. The databases would be growing much faster which would in turn result in more matches.
I'm hoping that like much of technology, prices of DNA tests will come down with increased competition in the marketplace and more efficient production practices. The sooner the better.
Now, back to my decision regarding which test to choose and why... I've decided to go with the mtDNA test. I will have my own DNA tested and be content with knowing the halogroup and likely migratory patterns of my maternal line. I can't justify asking my brothers or my uncle for a sample of their DNA. The case just isn't compelling enough to ask them to share something as uniquely personal as their DNA.
The best use of the test really is as an anthropological test, although it will add to a theory that two people are related through the direct maternal line. You will match the same results as other people who won't be related to you although because we test for three HVR regions, the discriminatory power is increased. It's never 100% positive, but will provide supporting evidence to a theory.
I can have my own mtDNA tested, there's no debate there. Because I'm a female I can't participate in a surname study with my own DNA, it's only done with a male's DNA. So then I must consider which male, if any, would I want to ask for a DNA sample for a Y-DNA test.
After giving this considerable thought, I came to the conclusion that there are only 2 male lines that I could pursue from a practical standpoint (because I don't know donors to ask for the others). One would be my father's line. I have two brothers and I'm pretty confident that I could persuade one or the other of them to donate their DNA if I really put my mind to it. Neither one of them has more than a polite interest in genealogy but either would probably cooperate if I made a solid case why they should. Making the case would be ever so much easier if there was someone else who I was trying to prove a relationship to. But there isn't. I think I would have a difficult time trying to make the case that there may be someone's DNA already in a database somewhere or someone's DNA may appear in a database sometime in the future that would come up as a match and then we would know that we are related to them but not necessarily how. To an avid genealogy fan, this doesn't sound like such a bad deal but I'm thinking my brothers would come back with, "you're kidding, right?" I have to admit, it isn't a compelling argument even to me.
The other line that I could pursue would be my maternal grandfather's line. I could ask my mother's brother to donate a sample of his DNA. To be honest, this line is much more interesting to me than my father's line and would be my "line of choice" to pursue if all else were equal. I have no idea how my uncle would feel about donating a sample of his DNA. We're not close, I understand he's showing symptoms of Alzheimer's disease (it runs in the family), and he's very hard of hearing. Trying to explain all this to him would be challenging to say the least. Again, it would be much easier to make the case if I could just say, "I think that person X might be related to us but I need a sample of your DNA to know for sure". But of course there is no "person X" so I can't say that. My maternal grandfather had two "cousins" who came to America that I haven't actually been able to establish a family connection with. It would be nice if a DNA test could establish that. The problem is, they don't have the same surname so they would be related to my grandfather through their mothers not their fathers. It's highly unlikely that their DNA would be a match with my uncle's.
If I were a male there would be no debate. I would have the Y-DNA test done and hope that a match comes up with someone at some point and be content with just learning my halogroup for now. (I've already determined that there are currently no surname studies being done on any of my eight great grandparents' surnames.)
If I had the DNA results of someone I thought might be a relative or someone suspect who was also willing to give a sample for a Y-DNA test, I would put forth the effort to explain it to my brothers or my uncle in an effort to establish a family connection. If there was a surname study being done that would be a compelling reason to pursue it too. But I don't think I'm willing to try to make that explanation and put them on the spot just to learn our halogroup.
In the early days of the telephone there weren't many people you could call. You were limited to only calling up the few other individuals who were inclined to have one of those contraptions. Over time, more and more people got telephones and the pool of people you could call up increased dramatically. Nowadays, almost everyone has a telephone. You could call up millions of people if you were so inclined. That's a good analogy to the current situation with Y-DNA genetic genealogy tests. Right now, relatively speaking, there aren't all that many names/results to compare your DNA with. But I believe in the future it will be commonplace for people to have these sorts of DNA tests done. The databases will be much larger, as will surname projects, and matches will be usual and expected. But the field isn't there yet. It will take time to get there and I think the biggest factor influencing the time is the cost of the tests. If you could have a test done for $19.99 instead of $100-$250, you'd see a lot more people signing up. The databases would be growing much faster which would in turn result in more matches.
I'm hoping that like much of technology, prices of DNA tests will come down with increased competition in the marketplace and more efficient production practices. The sooner the better.
Now, back to my decision regarding which test to choose and why... I've decided to go with the mtDNA test. I will have my own DNA tested and be content with knowing the halogroup and likely migratory patterns of my maternal line. I can't justify asking my brothers or my uncle for a sample of their DNA. The case just isn't compelling enough to ask them to share something as uniquely personal as their DNA.
