Which DNA test should I purchase?

[mellen]

There are 3 different family lines in our county with the same surname. All three lines came from northwest Germany. One male from each family line with the same surname is willing to do a DNA test to see if the three lines are related. Which DNA tests should I purchase for those 3 individuals?

[Earl Davis]

I might suggest a YDNA-37 to start. If that offers up more interesting questions then deeper testing could always follow later.

[Lklundin]

I might suggest a YDNA-37 to start. If that offers up more interesting questions then deeper testing could always follow later.

Just wondering, with the up to several hundred Y-DNA SNPs being found with Geno 2.0, would that not be useful for determining closeness of patrilineal relationships?

[Brunetmj]

Just wondering, with the up to several hundred Y-DNA SNPs being found with Geno 2.0, would that not be useful for determining closeness of patrilineal relationships?

Probably not. The geno 2 is good for establishing deep clade but it is not a STR test.

[tomcat]

Just wondering, with the up to several hundred Y-DNA SNPs being found with Geno 2.0, would that not be useful for determining closeness of patrilineal relationships?

Not really. For example if all three were identical for Geno Y SNP's you would only know they are related at the level of deep ancestry. In contrast, Y STR's would yield a time estimate to their most recent common ancestor, a much more useful estimate for relating Y to genealogy.

[MMaddi]

I might suggest a YDNA-37 to start. If that offers up more interesting questions then deeper testing could always follow later.

I agree with the general idea of a yDNA STR marker test. However, since all three lines share the same surname and geographical region of origin, a 67 marker test would be more informative. Assuming all 3 lines are related in the last few hundred years, 67 markers would give you a more accurate estimate of how long ago the common ancestor lived.

In a case like this, the most useful test is a yDNA STR test, not Family Finder or Geno 2.0. It may be that, after you've established approximately how recently the lines share a common ancestor, the Family Finder test could help hone in on the "time to most recent common ancestor."

[Lklundin]

In a case like this, the most useful test is a yDNA STR test, not Family Finder or Geno 2.0.

Yes, this makes sense.

I will explain why I brought up Geno 2.0 in this context.

Consider the Y-DNA STR test with 12 markers and a genetic distance of 0 - and based on that you can compute a Time to the Most Recent Common Ancestor - which will be quite distant, and unlikely to apply to the above case.

But it could happen in the above case, and it does happen in other cases.

Such two men with a GD=0 at 12 makers can be in different subclades, e.g. two different subclades of R1b1a2a1a1.

And that means that their MRCA _is_ the founder of R1b1a2a1a1 - and granted, the age estimate of for example that haplogroup has a wide spread. But it is still very concrete.

R1b1a2a1a1 is defined by a limited number of SNPs - on the order of a few dozen, I imagine.

Now think of the Geno 2.0, where two R1b-men can get SNPs that run into the hundreds. When these hundreds of SNPs get organized into a phylogenetic tree, then the most recent subclades in that tree cannot be that old.

Dating these many subclades will be difficult, but still if two men take Geno 2.0 and see that they share all but a couple out of 300 SNPs, then that places them very close to each other in this (admittedly yet to come) phylogenetic tree.

And knowing exactly where in the phylogenetic tree your MRCA is, is in my mind preferable to the list of probabilities that the TMRCA estimates yield.

So my point is, for males where there is no a priori indication of a close relation, I think the Geno 2.0 will gain increased relevance.

If others disagree, I will be happy to read why.

[tomcat]

[QUOTE=Lklundin;356358 ...
So my point is, for males where there is no a priori indication of a close relation, I think the Geno 2.0 will gain increased relevance.
...[/QUOTE]

In the case cited by the original poster, of three families in the same county, with the same surname, all hailing from NW Germany, one might conjecture (with the original poster) that shared location, shared surname and shared origin point to a shared genealogy and migratory history.

While it would be interesting to have Geno 2.0 results for a male of each family it would only confirm what is already known - shared deep ancestry or ancestry of origin - but leave unaddressed the conjecture of genealogical relationship.

To make a contrary case, as some are inclined to do, that Y STR profiles can converge and that Y STR profiles cannot be validly compared without accompanying and extensive SNP profiles ends in the incredulous coincidence of three families in the same county from the same region of Germany with the same surname AND wholly converged STR profiles!!!!