This is an example of comparing and analyzing the DNA of three persons known to be related. The table below compares their DNA haplotypes, i.e. the sets of numbers used to describe their DNA:

ID D
Y
S
3
9
3
D
Y
S
3
9
0
D
Y
S
1
9
/
3
9
4
D
Y
S
3
9
1
D
Y
S
3
8
5
a
D
Y
S
3
8
5
b
D
Y
S
4
2
6
D
Y
S
3
8
8
D
Y
S
4
3
9
D
Y
S
3
8
9
-
1
D
Y
S
3
9
2
D
Y
S
3
8
9
-
2
D
Y
S
4
5
8
D
Y
S
4
5
9
a
D
Y
S
4
5
9
b
D
Y
S
4
5
5
D
Y
S
4
5
4
D
Y
S
4
4
7
D
Y
S
4
3
7
D
Y
S
4
4
8
D
Y
S
4
4
9
D
Y
S
4
6
4
a
D
Y
S
4
6
4
b
D
Y
S
4
6
4
c
D
Y
S
4
6
4
d
D
Y
S
4
6
0
G
A
T
A
H
4
Y
C
A
I
I
a
Y
C
A
I
I
b
D
Y
S
4
5
6
D
Y
S
6
0
7
D
Y
S
5
7
6
D
Y
S
5
7
0
C
D
Y
a
C
D
Y
b
D
Y
S
4
4
2
D
Y
S
4
3
8
Colin 13 24 14 10 11 13 12 12 12 13 14 29 17 8 10 11 11 25 15 18 30 15 16 16 17 11 12 19 23 17 15 18 17 37 39 12 12
Ross 13 24 14 10 11 13 12 12 12 13 14 29 17 8 10 11 11 25 15 18 30 15 16 16 17 11 11 19 23 17 15 18 17 37 39 12 12
Bruce 13 25 14 10 11 13 12 12 12 13 14 29 17 8 10 11 11 25 15 18 30 15 16 16 17 11 12 19 23 17 15 18 17 37 39 12 12
Distance from reference: Zero One Two Three+

If you look carefully you will see that Bruce differs from Colin at DYS390. Since this is the only marker in which they differ, the genetic distance is said to be one; i.e. GD = 1. A genetic distance of 1 for 37 markers is a close match from which one would conclude that Bruce and Colin share a common ancestor. If you examine Ross you will see that he also differs from Colin but at GATAH4; in this case GD = 1. Ross and Bruce are GD=2

Bruce, Colin and Ross are known via genealogy research to share a common ancestor within four generations. The table below shows how the line splits:

Simple Tree

The vendor used for DNA analysis in the project is Family Tree DNA. Each participant is provided with a personal webpage for accessing and managing their results. One tool provided is known as the Family Tree DNA Time Predictor. When this tool is used to compare Colin and Ross one obtains the result shown below:

FTDNATiP Report

In comparing Y-DNA 37 marker results, the probability that Ross and Colin shared a common ancestor within the last...
Comparison Chart
Generations Percentage
4 59.15%
8 89.13%
12 97.51%
16 99.47%
20 99.89%
24 99.98%

Colin and Ross actually share an ancestor within 4 generations and the theoretical comparison predicted the probability that the TMRCA was less than or equal to 4 generations is 59.15% or 59%. Bruce and Colin share a common ancestor within 3 generations and in a separate calculation the theory predicted the probability of that in that case is 45.41% or 45%.

TMRCA - Time to Most Recent Common Ancestor

In the descendancy chart above you can see that Bruce and Colin's most recent common ancestor was 3 generations ago whereas with Ross and Colin the TMRCA is 4 generations ago. These numbers are actual TMRCA based on the genealogy. On this site predicted TMRCA are not computed by the FTDNATiP Report for two reasons: (1) it does not compute and export tables for groups of people and (2) the mutation rates are thought to be too high. TMRCA tables (with these mutation rates) and were generated using McGee's Y-DNA Comparison Utility. The theoretical ranges are colored red in the diagram below. The actual TMRCA colored yellow are expected to fall within the theoretical ranges shown 95% - 5% = 90% of the time. In this example they are all within range.

TMRCA Actual vs Theoretical Range

ID C
o
l
i
n
B
r
u
c
e
R
o
s
s
Colin 111 3 4
Bruce 1-19 37 4
Ross 1-19 3-24 37
Actual Theoretical (5% to 95%)
- Infinite allele mutation model is used
- Average mutation rate varies: 0.0026 to 0.0026
- Mutation rates from Heinilia, 2012
- Values on the diagonal indicate number of markers tested

37 Markers vs 67 Markers

The tables below are based on data or descendants of Robert Ferguson and Martha Baugh. They show the theoretical ranges tighten up as markers tested increase from 37 to 67 and more cells are now green.

37 Markers - Theoretical Range (5%-95%)

67 Markers - Theoretical Range (5%-95%)

Actual TMRCA

ID 1
6
1
1
5
9
1
3
2
8
2
1
1
0
6
2
9
9
4
2
8
0
7
1
1
3
1
6
9
1
1
8
4
6
6
161159 37 0-11 1-19 3-24 3-24 3-24
132821 0-11 37 1-19 3-24 3-24 3-24
106299 1-19 1-19 37 5-31 5-31 5-31
42807 3-24 3-24 5-31 37 0-11 0-11
113169 3-24 3-24 5-31 0-11 37 0-11
118466 3-24 3-24 5-31 0-11 0-11 37
ID 1
6
1
1
5
9
1
3
2
8
2
1
1
0
6
2
9
9
4
2
8
0
7
1
1
3
1
6
9
1
1
8
4
6
6
161159 67 0-9 1-15 2-19 2-19 4-23
132821 0-9 67 1-15 2-19 2-19 4-23
106299 1-15 1-15 67 4-23 4-23 6-27
42807 2-19 2-19 4-23 67 0-9 1-15
113169 2-19 2-19 4-23 0-9 67 1-15
118466 4-23 4-23 6-27 1-15 1-15 67
ID 1
6
1
1
5
9
1
3
2
8
2
1
1
0
6
2
9
9
4
2
8
0
7
1
1
3
1
6
9
1
1
8
4
6
6
161159 - 4 10 9 9 9
132821 4 - 10 9 9 9
106299 10 10 - 10 10 10
42807 9 9 10 - 8 8
113169 9 9 10 8 - 8
118466 9 9 10 8 8 -
Related Probably Related Possibly Related Probably UnRelated
- Infinite allele mutation model is used
- Average mutation rate varies: 0.0026 to 0.0036
- Mutation rates from Heinilia, 2012
- Values on the diagonal indicate number of markers tested

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