McGeachie Y - DNA Project

Welcome to the McGeachie Surname DNA Project.

The purpose of the McGeachie Surname DNA project is to collect as many Y Chromosome DNA test samples from males with the surname "McGeachie/McGeachy/McGechie" or variants, to compile the data into charts and try to find the Most Recent Common Ancestor.

We would also like to match those tests to find significant marker matches and finally try to find a geographical location or origin for the surname. Most DNA projects tend to happen after the conventional paper trail has died out. These projects are long term undertakings and as more and more participants join the project, we should be able to build a bigger picture of the surname spread throughout the world. The Y-Chromosome is passed from a father to his son and then onto his grandson and is usually unaltered for generations.

The Y Chromosome DNA test is currently the latest tool available to genealogists to help fill in the missing pieces of your family tree, whether it's finding relatives or family migration patterns etc. I have already setup a McGeachie Surname DNA Project page at Family Tree DNA's search site www.ysearch.org or click the link for the McGeachie ysearch page where you can search for other users with the same surname or variations of the surname.

Family Tree DNA offers 12, 25, 37 and 67 marker tests. However we would recommend either a 37 or 67 marker test for our project as these give the best chance of significant marker matches.

 

McGeachie Y-DNA Project History.

The McGeachie DNA project was started in June 2007 by David James McGeachie. With 16 participants at present, it was felt that in order for the project to proceed it would be necessary to make preparations for the data to follow. However, as more and more participants are added to the the data charts, we will define our own project modals. Finally, I'm on the trail of George McGeachie and family from Port Glasgow who was born around 1754. A DNA test may resolve this line of investigation.

Further to the information above regarding George McGeachie from Port Glasgow, I found another George McGeachie a (Sailer), and his spouse Margaret Watson, they had a Daughter Helen born 3rd Jan 1745 in Greenock Renfrew.

How to read the test results.

When we test the Y-Chromosome we are testing a marker called the Short Tandem Repeat (STR). STR's are short sequences of DNA that are repeated numerous times, these repeats are referred to as Allele. The variations in these marker repeats give the differences between individuals. Table 1 below is used to show 37 marker DNA test results. The set of numbers across the top of the table are DYS# (the actual marker names). They have no significance other than as an easy way to refer to the marker. Note:FamilyTree DNA refers to these numbers as Locus. The numbers down the left side of the table identify the participants ID in our DNA project. The next column in the table gives the participants name. The rest of the numbers in the table are the Allele (the number of repeats) for each participant at the specified DYS marker.

 

Table 1

ID

Name

37 Markers DYS#

 

3
9
3
3
9
0
1
9
3
9
1
3
8
5
a
3
8
5
b
4
2
6
3
8
8
4
3
9

3
8
9
|
1
3
9
2
3
8
9
|
2
4
5
8

4
5
9
a
4
5
9
b
4
5
5
4
5
4
4
4
7
4
3
7
4
4
8
4
4
9
4
6
4
a
4
6
4
b
4
6
4
c
4
6
4
d
4
6
0
H
4
Y
C
A
I
I
a
Y
C
A
I
I
b
4
5
6
6
0
7
5
7
6
5
7
0
C
D
Y
a
C
D
Y
b
4
4
2
4
3
8
0001
No 1
 132414111114121212131329170910111125151929151517171111192316151817373812
12
0002
No 2
 132514111113121212131429170910111125151830151616171111192317161817373912
12
0003
No 3
 132414101114121212131330180910111125151930151517171112192316151817373812
12

 

What does than mean.

After a participant has had their test results they have little meaning on their own. The value of the test results depends on how your results compare to other participants test results. Even when you have a match with someone else, it will only indicate that you and the person you match share a common ancestor. Depending on the number of markers tested and the number of matches will indicate with a certain degree of probability how long ago this common ancestor existed. It will not show exactly who this ancestor was. The more makers you have in common with someone, the more recently you have likely shared that most recent common ancestor (MRCA). The chart below helps illustrate those probabilities:

 

Chart 1

The Number of matching markers in a participants test. FTDNA offers 12, 25, 37 & 67 marker tests.
50% probability 
that the MRCA was no longer than this number of generations.
90% probability 
that the MRCA was no longer than this number of generations.
95% probability 
that the MRCA was no longer than this number of generations.
10 of 12
16.5
56
72
11 of 12
17
39
47
12 of 12
7
23
29
23 of 25
11
23
27
24 of 25
7
16
20
25 of 25
3
10
13
35 of 37
6
12
14
36 of 37
4
8
10
37 of 37
2 to 3
5
7
65 of 67
6
12
14
66 of 67
4
8
9
67 of 67
2
4
6

 

1 Generation is equal to 25 years (as used by Family Tree DNA).

As discussed above, the Y-Chromosome is passed from a father to his son and then to his grandson. The vast majority of the time the father passes an exact copy of his Y-Chromosome to his son. This means that the markers of the son and father are identical. However on rare occasions there is a mutation or change in one or more of the markers. This change is either an insertion or a deletion. An insertion is when an additional repeat is added to a marker. A deletion is when one of the repeats is deleted. Mutations occur at random.

This means it is possible for two distant cousins to match exactly on all markers while two brothers might not match exactly. Because of the random nature of mutations we must use statistics and probability to estimate the Time to The Most Recent Common Ancestor (TMRCA). The actual calculations of TMRCA are mathematically complex and depend on knowing the rate of mutation and the true number of mutations.

 

To Join the McGeachie Surname Y-DNA Project please click this link; Join The McGeachie Surname Y-DNA Project

Click here to view the McGeachie Y-DNA Project Results.