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Fergus(s)on DNA Project

John FERGUSON and Ann STUBBLESON

Times to Most Recent Common Ancestor

 dna

TMRCA
The numbers in red show how many generations removed each participant is from the family's most recent common ancestor. One of the difficulties in the computations to follow is comparing participants who are not of the same generation. Ignoring the difference and using a Family TMRCA based on the most distant tested generation is a reasonable approximation. It is equivalent to assuming that the haplotypes of persons whose generation does match the Family TMRCA are unchanged for the difference in generations being ignored. The approximation is reasonable because the probability of a haplotype changing from father to son is known to be low. Compared with other choices one might make, the choice of a most distant generation results in the largest Family TMRCA and presents a more severe test when compared with the 95% TMRCA. Finally, the numbers in blue are the resultant TMRCA.

TMRCA

The tables below compare the actual pairwise TMRCA as deduced from the above diagram with theoretical computations of the 95% TMRCA.
Actual TMRCA A
e
r
o
n		 J
o
n		 J
e
s
s
e		 C
h
r
i
s		 M
i
k
e		 H
e
r
m
a
n
Aeron_F._Ferguson 69 10 10 10 10 10
Jon_R_Ferguson 10 37 4 8 8 9
Jesse_Joe_Ferguson 10 4 67 8 8 9
Christopher_Allen_Ferguson 10 8 8 67 8 9
Mike_Ferguson III 10 8 8 8 67 9
Herman_White_Ferguson 10 9 9 9 9 37
95% TMRCA
Aeron_F._Ferguson 69 18 18 14 18 14
Jon_R_Ferguson 18 37 8 27 31 22
Jesse_Joe_Ferguson 18 8 67 24 28 22
Christopher_Allen_Ferguson 14 27 24 67 24 18
Mike_Ferguson III 18 31 28 24 67 27
Herman_White_Ferguson 14 22 22 18 27 37
0-9 Generations 10-19 Generations 20-29 Generations 30-39 Generations
- Infinite allele mutation model is used
- Average mutation rate varies: 0.0033 to 0.0049
- Mutation rates from Chandler, Little & Hutchison
- Values on the diagonal indicate number of markers tested
- Probability is 95% that the TMRCA is no longer than indicated
In these cases all the actual TMRCA are less than the 95% numbers as they probably should be. It is concluded the resultant set of pairwise actual TMRCA defined by the genealogical structure is consistent with the corresponding set of pairwise TMRCA computed from the DNA mismatches.


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