Crest

Fergus(s)on DNA Project

Colonel Robert Ferguson (1701-1794)

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 5% and 95% TMRCA.
Actual TMRCA F
r
a
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L
e
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e		 J
a
m
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s

M
a
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k 		J
a
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s

D
a
v
i
d		 D
a
v
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d

N		 K
e
n
n
e
t
h

W
a
r
r
e
n		 D
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e
l

B
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t		 E
v
e
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e
t
t

D
o
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a
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d		 J
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f
f
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y

B
r
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d
o
n
Frank_Lemoyne_Ferguson 66 8 8 8 8 7 8 8
James_Mark_Ferguson 8 66 7 7 5 8 4 6
James_David_Ferguson 8 7 75 7 7 8 7 7
David_N_Ferguson 8 7 7 66 7 8 7 7
Kenneth_Warren_Ferguson 8 5 7 7 66 8 5 6
Daniel_Burt_Ferguson 7 8 8 8 8 37 8 8
Everett_Donald_Ferguson 8 4 7 7 5 8 37 6
Jeffrey_Brandon_Ferguson 8 6 7 7 6 8 6 37
95% TMRCA
Frank_Lemoyne_Ferguson  66 18 21 38 21 14 14 14
James_Mark_Ferguson  18 66 12 28 12 8 8 8
James_David_Ferguson  21 12 75 31 14 8 8 8
David_N_Ferguson  38 28 31 66 24 27 27 27
Kenneth_Warren_Ferguson  21 12 14 24 66 8 8 8
Daniel_Burt_Ferguson 14 8 8 27 8 37 8 8
Everett_Donald_Ferguson  14 8 8 27 8 8 37 8
Jeffrey_Brandon_Ferguson 14 8 8 27 8 8 8 37
5% TMRCA
Frank_Lemoyne_Ferguson  66 3 4 13 4 1 1 1
James_Mark_Ferguson  3 66 1 8 1 0 0 0
James_David_Ferguson  4 1 75 9 2 0 0 0
David_N_Ferguson  13 8 9 66 6 6 6 6
Kenneth_Warren_Ferguson  4 1 2 6 66 0 0 0
Daniel_Burt_Ferguson 1 0 0 6 0 37 0 0
Everett_Donald_Ferguson  1 0 0 6 0 0 37 0
Jeffrey_Brandon_Ferguson 1 0 0 6 0 0 0 37
0-9 Generations 10-19 Generations 20-29 Generations 30-39 Generations
- Infinite allele mutation model is used
- Average mutation rate varies: 0.0034 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
For the most part the actual TMRCA are bracketed by the 5% and 95% numbers as they probably should be. Some comparisons to David are outside the range, dropping the lower range to the 1% TMRCA captured James Mark and James David but not until a 0.1% TMRCA was the comparison with Frank captured. There is good reason to suspect the genealogy as it applies to David or Frank is in error.

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