Byrd DNA Study

Date: [unknown]
Surnames/tags: Byrd Bird Schermerhorn

This is the project page for the Byrd DNA Study, examining the Common Genome of Descendants of Francis Bird. Circumstantial evidence suggests his parents were Joshua Byrd and Drusilla Bell, though the origins of both parents are unknown. DNA tests prove a recent common ancestor between descendants of Francis Bird/Rhoda Schermerhorn and descendants of Benjamin Bird/Elizabeth Allison, but suggest that:

• the Bird line is not descended from the Bird family of New Castle Co., Delaware
• Francis Bird is not directly descended from the Allison family of Maryland
• the DNA match comes from MRCA relationship with the unknown wife of Benjamin Allison

Oral history suggests paternal descent from John Byrd and his wife Sarah of Northumberland Co., Virginia but has never been proven.

Contents 1 Definitions 2 Methodology 3 Cohort 1 4 Cohort 2 5 Cohort 3 6 Endnotes

Definitions

• MRCA = most recent common ancestor(s).
• cohort = a group of DNA samples all descended from the same MRCA.
• cohort-pair = two DNA samples from different cohorts that are tested against each other
• triangulated match = three sets of matches between three DNA samples in which the DNA segment of a particular chromosome is common to all three samples and the relationship between all samples is third cousin or greater.^[1]
• IBD match = a match between two DNA samples in which the minimum segment is at least 10 cMs, indicating a match that is "identical by descent" with a common ancestor within the last 500 years.^[2]
• threshold match = a match between two DNA samples in which the minimum segment is 7 cMs, the historically accepted minimum segment size for a moderately confident likelihood of a single MRCA.^[3] For purposes of this study a threshold match which exceeds 9.99 cMs is an IBD match, though it is also included as a threshold match when calculating totals for threshold matches.
• multi-chromosomal match = matches between two DNA samples on more than one chromosome.

Methodology

DNA matching was undertaken at GEDmatch using the default measures for One-to-One Autosomal Comparison except for the minimum segment cM size which was set to a numerical value of 5, the minimum segment size for negligible false-positives.^[4] Documented false positives were likewise eliminated.^[5] When dealing with large data sets, telltale traces of ancient, degraded DNA commonality seem to be:

• statistically significant,^[6] valid matches^[4] between samples from different cohorts; and
• matches between different cohort-pairs along the opposite autosome; and
• repetition of matches between different cohort-pairs on different segments of the same chromosome, particularly where those segments adjoin or are nearly-adjoined; and
• residual threshold matches.

As a rule of thumb, "identical by descent" blocks longer than 4 cMs date from 500-1,500 years, while blocks longer than 10 cM date from within the last 500 years.^[2]

Triangulated matches confirm existence of and/or identity of MRCA. Statistically significant IBD match rate strongly implies existence of MRCA within 500 years. Statistically significant threshold match rates below 10 cMs and/or valid match rates strongly imply existence of MRCA within last 1,500 years. Statistically significant multi-chromosomal rates are supporting evidence of an MRCA within last 500 years.

Cohort 1

Cohort	MRCA	Samples
1A	Joshua Merritt Bird/Elizabeth Cheatham	HC3420302, M836948, A485847, A984070
1B	John Owens Bird/Permelia Hardin	DP3782771, WR5516898, MX6303372, NK5428542, KG2043463,[7] PY1470082
1C	John Owens Bird/Permelia Hardin AND Martha Bird/Dorman Chesser	M811320,[8]A447996, EA5680299, EY6972268

Relations	Kits	MRCA	Chr	cMs
4th C	HC3420302/DP3782771/A485847	Francis Bird/Rhoda Schermerhorn	16	18.0

IBD Matches

Cohorts	Kits	Significance
1A v 1B	HC3420302/DP3782771 HC3420302/WR5516898 HC3420302/MX6303372 HC3420302/NK5428542 HC3420302/KG2043463 M836948/DP3782771 M836948/WR5516898 M836948/MX6303372 A485847/DP3782771 A485847/MX6303372 A984070/DP3782771 A984070/WR5516898 A984070/NK5428542	54%
1C v 1A	M811320/HC3420302 M811320/M836948 M811320/A485847 M811320/A984070 EA5680299/A485847 EA5680299/A984070 A447996/HC3420302 EY6972268/A984070	50%

Cohort 2

Cohort	MRCA	Samples
2A	Benjamin Bird/Elizabeth Allison	A097930,[9] QS7332580, M142433, G189020, JR3751106, T987112, A564262, A475891, M416339
2B	Ann Bird/Jesse Bounds	XH5402324, Z209024, M130935, WJ9630791, A306614, A424955
2C	James Bird/Mary Ashford	T808876, MY4074858, A268541, YR3867033
2D	Mary Bird/James Armstrong	M915741, US7857087
2E	Susannah Bird/George Miller	A892823, A833172

Cohort 2A: IBD Matches

There is a statistically significant IBD relationship between descendants of Benjamin Bird/Elizabeth Allison and the other descendants of Thomas Bird/Sarah Empson. This indicates they share a common ancestor within the past 500 years, with the New Castle Co. family being the most likely candidate.

Cohort	Kits	Significance
2A v 2B	XH5402324/G189020 M130935/G189020 A306614/A475891	6%
2A v 2C	A564262/A268541 YR3867033/M416339	6%
2A v 2D	US7857087/M416339	6%
2A v 2E	A833172/QS7332580	8%

There is a statistically significant IBD relationship between descendants of Francis Bird/Rhoda Schermerhorn and Benjamin Bird/Elizabeth Allison, indicating a common ancestor within the past 500 years.

Cohorts	Kits	Significance
1A vs 2A	HC3420302/A097930 M836948/A097930 A485847/T987112	9%
1B vs 2A	A097930/DP3782771 A097930/WR5516898 A097930/MX6303372 QS7332580/M811320 QS7332580/EA5680299 M416339/EY6972268 M416339/EA5680299	8%

There is not a significant IBD relationship between descendants of Francis Bird/Rhoda Schermerhorn and other descendants of Thomas Bird/Sarah Empson however. This indicates that Francis Bird was not descended from the New Castle Co. family and that any IBD matches are likely from another relationship that is merely coincidently with one of that family's descendants.

Cohorts	Kits	Significance
1 v 2B	Z209024/WR5516898	<1%
1 v 2C	YR3867033/A447996	1%
1 v 2D	-----	0%
1 v 2E	-----	0%

Cohort 3

Cohort	MRCA	Samples
3A	Charles Allison/Barbara Moore	AL7141039, H521929, PJ2763386
3B	Benjamin Allison/unknown wife	A097930, QS7332580, T987112, A564262, A475891
3C	Richard Allison/Sarah Cheshire	WQ1040358, MT4188120, LP9911906, BA7664386

IBD Matches: Cohort 1 vs Cohort 3

There is a statistically significant IBD relationship between descendants of Francis Bird/Rhoda Schermerhorn and descendants of Benjamin Allison and his unknown wife, but no statistically significant IBD relationships with descendants of the two other Allison brothers.

Cohort	Kits	Significance
1 v 3A	-----	0%
1 v 3B	QS7332580/M811320 QS7332580/EA5680299 QS7332580/EA5680299 T987112/A485847 T987112/EA5680299 T987112/WR5516898 A097930/HC3420302 A097930/M836948 A097930/DP3782771 A097930/WR5516898 A097930/MX6303372	16%
1 v 3C	-----	0%

Endnotes

1. ↑ Debbie Wayne (2016). Genetic Genealogy Journey: Triangulating Autosomal DNA. debbiewayne.com
2. ↑ ^{2.0 2.1} Ralph P, Coop G (2013). The Geography of Recent Genetic Ancestry across Europe. PLOS Biology 11(5):e1001555.
3. ↑ Autosomal DNA match thresholds, International Society of Genetic Genealogy Wiki, edited on 17 August 2020.
4. ↑ ^{4.0 4.1} Durand EY, Eriksson N, McLean CY. Reducing pervasive false positive identical-by-descent segments detected by large-scale pedigree analysis. Molecular Biology and Evolution advance access publication online 30 April 2014.
5. ↑ Matching segments identified as possible "large-scale population pile-up region(s)“ indicative of identity by chance rather than identify by descent were eliminated. See Li H, Glusman G, Hu H, Shankaracharya, Caballero J, Hubley R, et al. (2014) Relationship Estimation from Whole-Genome Sequence Data. PLoS Genet 10(1): e1004144.
6. ↑ Statisical significance, Wikipedia, retrieved on 17 March 2021.
7. ↑ Comes from a living descendant of Francis Marion Bird.
8. ↑ Comes from a living descendant of Ronnie Mitchell.
9. ↑ Comes from a living descendant of Evelyn Williams.