Genealogists' Forum - We have branches everywhere!



Go Back   Genealogists' Forum - We have branches everywhere! > Research > DNA Questions

Reply
 
Thread Tools Display Modes
  #1  
Old 03-12-20, 18:22
RForbes RForbes is offline
Member
 
Join Date: Dec 2020
Posts: 8
Red face When is a match, a match...? (Tracking down Andrew Forbes)

Hi there!

First... some background

I've been trying to substantiate whether Andrew Forbes, who lived in Johnstone, Renfrewshire (m. 1792) is the father of my 4x Great Grandfather, William Forbes (b. 1806-11) who was a blacksmith in Girvan, Ayrshire.

I have some reasons to suspect this patrilineage (despite the substantial distance between Girvan & Johnstone):
  • William Forbes' sister, Helen, was born in Johnstone, Renfrewshire.
  • William's first born son was named Andrew. (Consistent with Scottish Naming Patterns).
  • Andrew Forbes had a son named William, born 1806, according to a birth record. Right timeline.
  • Most of Andrew Forbes' children worked as blacksmiths. As did most of William Forbes' children.

Testing the theory with DNA

What I had hoped to accomplish was to provide another layer of substantiation to this theory before I moved on in my research.

The documentation all points positively, but would DNA substantiate or contradict the theory?

So I built a large family tree and tracked down three known distant descendants of Andrew Forbes who had all taken DNA tests: two six cousins, and a fourth cousin (2 times removed). Two of the descendants weren't interested. One of the sixth cousins had agreed to export her Ancestry.com file and I did a Autosomal One-to-one Comparison on GEDmatch.

These were the GEDmatch comparison results:
Largest segment = 4.4 cM
Total Half-Match segments (HIR) 18.3cM (0.511 Pct)
5 shared segments found for this comparison.
417967 SNPs used for this comparison.
52.479 Pct SNPs are full identical
My question for the forum is whether this provides credence to the theory that William is Andrew's son? It looks to me like the result is consistent with a sixth cousin and therefore doesn't contradict anything (?), but how different in terms of cM would a random person (a control) be from a sixth cousin? Is there a next step I should take?
Reply With Quote
  #2  
Old 03-12-20, 18:32
kiterunner's Avatar
kiterunner kiterunner is online now
Administrator
 
Join Date: Aug 2009
Location: Nottingham
Posts: 25,268
Default

I guess you could do some similar comparisons with random people and see what the results look like?

If the largest segment is only 4.4 cM it looks to me as though it could just occur by chance, but then if you are looking at known sixth cousins, most of them will not come up as DNA matches anyway. For instance, according to FamilyTreeDNA, the chance of having a DNA match with a sixth cousin is less than 2%.
__________________
KiteRunner

Family History News updated 29th Feb
Findmypast 1871 census update
Reply With Quote
  #3  
Old 03-12-20, 19:22
kiterunner's Avatar
kiterunner kiterunner is online now
Administrator
 
Join Date: Aug 2009
Location: Nottingham
Posts: 25,268
Default

Also, I don't know much about Y-DNA testing, but as it seems you are working on the male line all the way back, you could look into whether there is a Forbes Y-DNA project and whether it would be worth you (or a male Forbes relative such as brother, father or uncle if you are female) doing a Y-DNA test.
__________________
KiteRunner

Family History News updated 29th Feb
Findmypast 1871 census update
Reply With Quote
  #4  
Old 03-12-20, 19:33
kiterunner's Avatar
kiterunner kiterunner is online now
Administrator
 
Join Date: Aug 2009
Location: Nottingham
Posts: 25,268
Default

And a non-DNA question - have you found a birth / baptism record for Helen showing that she was Andrew's daughter?
__________________
KiteRunner

Family History News updated 29th Feb
Findmypast 1871 census update
Reply With Quote
  #5  
Old 03-12-20, 20:30
RForbes RForbes is offline
Member
 
Join Date: Dec 2020
Posts: 8
Default

Quote:
Originally Posted by kiterunner View Post
I guess you could do some similar comparisons with random people and see what the results look like?

If the largest segment is only 4.4 cM it looks to me as though it could just occur by chance, but then if you are looking at known sixth cousins, most of them will not come up as DNA matches anyway. For instance, according to FamilyTreeDNA, the chance of having a DNA match with a sixth cousin is less than 2%.
Okay I've looked at 60 random GEDMatch results and compared, the results suggest a mean cM of 3.96885. (Standard Deviation: 2.23).



I have a feeling this suggests to me that while the DNA comparison can't disprove the theory, it cannot substantiate it either, since the result is virtually identical to a comparison with a random subject. What do you think?

Quote:
And a non-DNA question - have you found a birth / baptism record for Helen showing that she was Andrew's daughter?
Excellent question: no I've never found a birth record for Helen. That's been the biggest gap in the documentation. The gap was never a dealbreaker for me (there are other children that have lacked birth records in the family), but it's partly why I've tried to search out as many means as possible of substantiating the theory.

Helen Forbes appears in the 1851 and 1861 Scotland census but her birth date jumps from 1801 to 1811 between the two censuses. I think the reason for the discrepency is the census lazily chose '40' and '60' for her age. However I can confirm that it's the same Helen in both censuses because she was living with two of her nieces; this closeness was documented in the nieces' death and marriage certificates.

I've never identified Helen in the 1841 census, nor have I identified a death record.

Andrew Forbes (m. 1792) had three documented children for which birth records can be found on ScottishPeoples.gov.uk:
Agnes Forbes (b. 1792, d. unknown)
John Forbes (b. 1804)
William Forbes (b. 1806, d. ~1845)
Andrew Forbes (b. 1810, d. 1839) is usually assumed in genealogical research to be another child of Andrew Forbes.

Since the sixth cousin that my DNA was compared against was related to Andrew Forbes via Andrew, there is the remote possibility that it is Andrew, not William, who was not related to Andrew Sr.

Quote:
Also, I don't know much about Y-DNA testing, but as it seems you are working on the male line all the way back, you could look into whether there is a Forbes Y-DNA project and whether it would be worth you (or a male Forbes relative such as brother, father or uncle if you are female) doing a Y-DNA test.
I am working the male line as far back as I can, yes. I am interested in doing a Y-DNA test in the future, but I'm a bit skeptical of the relevance of the Forbes Y-DNA project to me that I've seen, because my Forbeses don't appear to have come from Aberdeen. My suspicion is the Forbeses in my line probably settled in Johnstone in the 1790s from Perthshire (Blair Atholl?) or Argyll.

One of the most interesting little finds I've found was "Andrew Forbes of Johnstone" cited as a subscriber in 1794 and 1795 to a series of volumes of puritan sermons. Which suggests Andrew may have been literate and religious (and certainly not a jacobite!).

https://books.google.ca/books?id=QRxhAAAAcAAJ&
https://books.google.ca/books?id=B-pNAQAAMAAJ&dq

Last edited by RForbes; 03-12-20 at 20:32.
Reply With Quote
  #6  
Old 03-12-20, 22:35
Olde Crone Olde Crone is online now
Member
 
Join Date: Aug 2009
Posts: 4,766
Default

I know you say this family has no connection to the Aberdeen Forbes, but just to humour me, did your Andrew marry a Nesbitt? I have a parallel family with a Helen Forbes missing in 51 and 61, but found at death in Nigg.

OC
Reply With Quote
  #7  
Old 03-12-20, 22:50
kiterunner's Avatar
kiterunner kiterunner is online now
Administrator
 
Join Date: Aug 2009
Location: Nottingham
Posts: 25,268
Default

I agree with you about the results of your GEDmatch comparisons. I will see if I can find anything non-DNA-related to help with the Forbeses.
__________________
KiteRunner

Family History News updated 29th Feb
Findmypast 1871 census update
Reply With Quote
  #8  
Old 03-12-20, 23:38
kiterunner's Avatar
kiterunner kiterunner is online now
Administrator
 
Join Date: Aug 2009
Location: Nottingham
Posts: 25,268
Default

There is a Helen Forbes death with MMN Miller, 1864, age 55, but the district is Latheron, so seems unlikely to be the right person unless she had family in that area.
__________________
KiteRunner

Family History News updated 29th Feb
Findmypast 1871 census update
Reply With Quote
  #9  
Old 04-12-20, 01:16
RForbes RForbes is offline
Member
 
Join Date: Dec 2020
Posts: 8
Default

Quote:
Originally Posted by Olde Crone View Post
I know you say this family has no connection to the Aberdeen Forbes, but just to humour me, did your Andrew marry a Nesbitt? I have a parallel family with a Helen Forbes missing in 51 and 61, but found at death in Nigg.

OC
I am afraid I do not believe this Andrew is the same as your Andrew. I know of the Nigg-based Helen because I've come across her in my own research, but 'my' Helen reported in the 1861 Census she was born in Johnstone and it appears she never left Renfrewshire (there's a possibilty she followed her niece to Northern Ireland when her niece and new husband moved to Enniskillen during the 1870s - they later returned to Renfrewshire.)
Reply With Quote
  #10  
Old 04-12-20, 08:55
Olde Crone Olde Crone is online now
Member
 
Join Date: Aug 2009
Posts: 4,766
Default

Ah right, thankyou, it was a long shot, but I have known of longer shots in this family.

OC
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT. The time now is 10:14.


Hosted by Photon IT

Powered by vBulletin® Version 3.8.7 PL3
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.