The DNA evidence shows a possible problem in my McPherson descent, in particular in my line back to Stephen, son of Daniel McPherson, but the evidence is mixed. If my descent is wrong as indicated, it means that my McPherson family is actually descended from a Landon family.
I have abundant autosomal matches to descendants of James and Juliet McPherson, making it pretty certain that I’m descended from at least one of them. I have a smaller number through James’s mother Sarah, which corroborates specifically James.
The Y chromosome is passed from father to son and so can make long-range determinations of male-line relationships. Through the McPherson DNA project, as of 2022-03-30, eight documented descendants of Daniel, some through Stephen, have published results of Y chromosome tests.ref All but one match each other, but the one exception (MK49491) is a descendant of James and Juliet. Unfortunately, most do not provide lines of descent, making further inference difficult.
So far, I know of two male-line descendants of James and Juliet who have had some kind of Y chromosome test. One is that above, and the other is visible in my personal 23andMe account. Their tests match (both inside I2). I have large autosomal matches to both, which show that I am related to them in some way.
Here is a chart with the relevant descents:
| Daniel McPherson | ||
| Stephen McPherson | ||
| Joseph McPherson | ||
| John McPherson | ||
| James D. McPherson | ||
| William Pyott McPherson (1855–1937) | Joel McPherson (my great-great-grandfather) | |
| James Mason McPherson (1887–1981) | ||
| James “Hap” McPherson (1914–2002) | George O. McPherson (1915–2000) | |
| R. McPherson (*1941) | M2 | |
| M1 | ||
M1 and M2 have been tested as haplogroup I2, while Daniel and Stephen have several descendants all matching as haplogroup R1a (specifically R1a-FT110819). Thus, they are not related in a male line.
M1 has done a deeper STR test, and his signature is nearly an exact match for several men named Landon. It is thus nearly certain that M1 and M2 both descend patrilineally from this Landon family instead of Daniel McPherson.
One generation is therefore wrong. The key question is which. If it’s one of the first few, then I am also descended from the Landons rather than early McPhersons. But if it’s only in the William Pyott branch, then my descent is unaffected.
The generations from Stephen down to James do not have good documentation, and I’ve always had doubts about them. The information about M2’s descent was gotten second-hand.
The fact that I am known to be related to M1 and M2 eliminates many theories about their paternity; they surely are descended from James and/or Juliet, just not in a male line.
Most scenarios in which I am still descended from Daniel posit a McPherson family adopting a near relative. For example, William Pyott is more than seven years younger than his youngest sibling; perhaps he was an illegitimate son of one of his supposed sisters. A family might also have adopted a maternal nephew as one of their own children. On the other hand, William could simply be Juliet’s son by another man.
I searched for the name Landon in places where McPhersons lived, and found nothing in the early generations. But, the sparsely populated Caddo County of Oklahoma that William moved to did have Landon families; it is hard to believe this is coincidence since this is not a common name. However, James Mason was born in Tennessee, before the family moved.
Autosomal segment sizes can be used to approximate the number of generations separating two DNA matches, by taking logarithms. This technique should be used with caution, since DNA transmission is random, and the more distant a relation, the more the estimate tends to understate the number of generations. Also, different testing services have slightly different measurement standards. Nevertheless, it might give some indication. A scenario such as a half-relative or an adopted illegitimate grandson would add one generation to the documented number.
In this table, C and V are my mother and my maternal aunt, and KM and AM are two sisters who are great-grandchildren of William Pyott by one of his daughters, and LB is a great-great-grandchild of William. These are the only matches available since this is from two different testing services:
| Comparison | Match size | Estimated generation gap | Documented gap |
|---|---|---|---|
| C vs. M1 | 16 cM | 8.88 | 8 |
| C vs. M2 | 95 cM | 6.29 | 7 |
| V vs. M2 | 140 cM | 5.74 | 7 |
| C vs. KM | 0 cM | ∞ | 7 |
| C vs. AM | 73 cM | 6.69 | 7 |
| V vs. KM | 65 cM | 6.84 | 7 |
| V vs. AM | 89 cM | 6.41 | 7 |
| C vs. LB | 45 cM | 7.39 | 8 |
| V vs. LB | 70 cM | 6.74 | 8 |
| KM vs. M2 | ~300 cM | 4.65 | 5 |
| AM vs. M2 | ~400 cM | 4.24 | 5 |
The lack of any match between C and KM is somewhat unexpected, but these things sometimes happen.
So, it does not appear that the estimated gap is systematically larger than the documented gap.
I continue to seek out male McPhersons more closely related to take a Y-DNA test. A single one might resolve this question decisively.