DNA Detail for the Bird DNA Study

Date: [unknown]

This is the detail page for the Bird DNA Study. Genealogists may contact the project managers for specific research information.

Currently there are two cohorts of DNA descendants of Francis Bird and Jane Littleton of Rock Creek parish (1725) in modern Washington D.C. and historical Prince George's/Frederick/Montgomery Cos. in Maryland:

• Cohort 1 contains 15 samples from descendants of their great grandson Francis Bird his first wife Rhoda Schermerhorn via their son John Bird, referred to as "Bird-#" when referenced individually; and
• Cohort 2 contains 10 samples from descendants of their daughter Mary Bird, referred to as "Allison-#" when referenced individually.

Numerous other samples were grouped into cohorts for purposes of testing. They are:

• Cohort X1 = 6 samples that share the triangular match w/ Cohort 1 on chromosome 16 and 1 sample descended from same. Two are native to Eire, three to England and one to America.
• Cohort X3 = 15 samples descended from Sheridan families w/ ties to County Cavan, Eire.
• Cohort X5 = 8 samples descended from Bell families w/ ties to northern Eire.
• Cohort X7 = 13 samples descended from Maolmordha O'Riley and Mary Hull.
• Cohort X8 = 11 samples descended from Thomas Riley and Sarah Webb.

Contents 1 Definitions 2 Methodology 3 Results 3.1 Generation 1 3.1.1 ♂ Admixture w/ unknown Irish 3.1.2 ♀ Admixture w/ County Cavan "Sheridans" 3.1.3 ♀ Admixture w/ County Cavan "Rileys" 3.1.4 ♀ Admixture w/ County Meath "Rileys" 3.2 Generation 3 Spouse 3.2.1 ♀ Admixture w/ Scots-Irish "Bells" 3.3 Generation 4 Spouse 3.3.1 ♀ Admixture w/ Dutch "Kwiks" 4 Sources

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]
• sub-threshold match = a match between two DNA samples in which the minimum segment is 5 cMs, the minimum segment size for negligible false-positives.^[3]
• 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.^[4] 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 (MC) = matches between cohort-pair that occur on more than one chromosome.
• stippling = small matches on the same or opposite chromosome between two cohort-pairs as distinguished from another cohort-pair (which may or may not include one of the same samples from the first cohort-pair) with a match on the same or opposite chromosome upon a different segment.

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. 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^[3] between samples from different cohorts; and
• matches between different cohort-pairs along the opposite autosome; and
• stippling, a repetition of matches between different cohort-pairs on different segments of the same chromosome, particularly where those segments adjoin or are nearly- adjoined; and
• a pattern of sub-threshold matches among different cohort-pairs accompanied by one or more residual threshold matches.

As a rule of thumb, 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.

Results

Cohorts 1 & 2 were tested against each other as well as against a number of unrelated samples to determine relation.

• ▲Triangulated match▲Bird-1/Bird-2/Bird-5/Bird-7/Bird-9/Allison-5 on Chr. 14 @ 11.2 cMs
• ▲Triangulated match▲Bird-1/Bird-2/Bird-3/Bird-5/Bird-7 on Chr. 16 @ 18 cMs
• ▲Triangulated match▲Bird-1/Bird-2/Bird-3/Bird-5/Bird-7/Irish-1/Irish-2/Irish-3/Irish-4/Irish-5/ on Chr. 16 @ 10.3 cMs
• ▲Triangulated match▲Bird-3/Bird-5/Kwik-1 on Chr. 5 @ 9.4 cMs
• ▲Triangulated match▲Bird-5/Bird-9/Bird-12/Sheridan-5/Sheridan-6 on Chr. 6 @ 7.6 cMs
• ▲Triangulated match▲Bird-10/Bird-15/Sheridan-7 on Chr. 22 @ 7.1 cMs

Generation 1

• ▲Triangulated match▲Bird-1/Bird-2/Bird-5/Bird-7/Bird-9/Allison-5 on Chr. 14 @ 11.2 cMs

These triangulated matches prove common descent from Francis Bird the immigrant and his wife Jane Littleton of Rock Creek parish in Generation 1. The matches are conclusively dated to 1725-1727.

All samples from Cohort 1 are descended from Francis Bird and his first wife Rhoda Schermerhorn in Generation 4. The sample from Cohort 2 is descended from Mary Bird and her husband Benjamin Allison in Generation 2. The significance level for threshold matches between cohorts is 19%.

There is an intervening "Bird" surname in the descent of Cohort 2. In Generation 3 - Thomas Allison married Cassandra Bird.

• There is a statistically significant IBD relationship (6%) between their descendants and descendants of Thomas Bird/Sarah Empson, indicating that Benjamin was a scion of the New Castle, Delaware Birds.
• There is not a statistically significant IBD relationship (<1%) between descendants of Francis Bird/Rhoda Schermerhorn and other descendants of Thomas Bird/Sarah Empson, indicating that Francis Bird was not related to the New Castle Co. Birds.
• There is not a statistically significant relationship (<0%) between descendants of Francis Bird/Rhoda Schermerhorn and descendants of the other Allison brothers, indicating that Benjamin Allison was not the source of the matching DNA.

♂ Admixture w/ unknown Irish

• ▲Triangulated match▲Bird-1/Bird-2/Bird-3/Bird-5/Bird-7 on Chr. 16 @ 18 cMs
• ▲Triangulated match▲Bird-1/Bird-2/Bird-3/Bird-5/Bird-7/Irish-1/Irish-2/Irish-3/Irish-4/Irish-5/ on Chr. 16 @ 10.3 cMs

The first triangulated match proves common descent from Francis Bird of Washington Co., Kentucky and his first wife Rhoda Schermerhorn of Generation 4. The matches are conclusively dated to 1820-1822.

The second is part of an older and more extensive match-set that appears to be Irish, pre-immigration and to have descended via the paternal line of Francis Bird the immigrant of Generation 1. It is found in five additional samples outside Cohort 1 - designated collectively as Cohort X1 - two of which are native to Ireland, two to England and one to America.

Four samples of Cohort 2 likewise share threshold matches with Cohort X1, three of which are IBD. The highest cMs counts (17.4 and 16.8) occur amongst the two Irish samples (County Donegal and Republic of Ireland, respectively).

When considered in their totality, these matches suggest the following:

• a genetic migration to Scotland after 1641 (Scottish Borders samples)
• a genetic migration to America circa 1724 (via Francis Bird the immigrant)
• a genetic migration to County Donegal prior to 1824 (County Donegal sample)
• a genetic migration further south in Ireland ("Gall" family sample)
• three other possible migrations or sub-migrations to America and England.

♀ Admixture w/ County Cavan "Sheridans"

• ▲Triangulated match▲Bird-5/Bird-9/Bird-12/Sheridan-5/Sheridan-6 on Chr. 6 @ 7.6 cMs
• ▲Triangulated match▲Bird-10/Bird-15/Sheridan-8 on Chr. 22 @ 7.1 cMs

These triangulated matches prove common descent from an unknown couple in County Cavan sometime prior to 1724. This may suggest descent from the unknown wife of John Bird, likely a granddaughter of Hugh Aodh Riley.

The first is with descendants of Margaret Sheridan/Patrick Keogan. Their ancestry cannot yet be traced beyond County Cavan in the early 1800s.

The second is with descendants of Bryan O'Sheridan/Catherine McCabe. Their ancestry cannot yet be traced beyond County Cavan in the late 1770s.^[7]

♀ Admixture w/ County Cavan "Rileys"

The are extensive matches with descendants of Maolmordha O'Riley/Mary Hull of County Cavan, Eire. There are no triangular matches but there are:

• 4 IBD matches;
• a 14% significance rate among 42/298 threshold matches;
• a 38% significance rate among 113/298 sub-threshold matches; and
• a 19% significance rate among 58/298 multi-chromosomal matches.

Unlike the preceding matches with the Sheridans of County Cavan, these matches are found in both Cohort 1 and Cohort 2. This suggests descent from an unknown couple in northern Eire sometime prior to 1724. They appear to descend or intertwine with the Riley family of County Cavan and may suggest descent from the ancestors of the biological father of Jane Littleton, believed to be a grandson of Hugh Aodh Riley.

♀ Admixture w/ County Meath "Rileys"

The are extensive matches with 12 descendants of Thomas Riley/Sarah Webb of Accomack Co., Virginia. There are no triangular matches but there are:

• X IBD matches;
• a X% significance rate among X/253 threshold matches;
• a X% significance rate among X/253 sub-threshold matches; and
• a X% significance rate among X/253 multi-chromosomal matches.

The matches are found in both Cohort 1 and Cohort 2. They are believed to derive from the maternal line of Jane Littleton.

Generation 3 Spouse

♀ Admixture w/ Scots-Irish "Bells"

Cohort 1 was tested against Cohort X5, the latter containing 7 samples from descendants of Bell families with ties to northern Ireland but for which there is no MRCA. The source of this DNA is presumed to be Drusilla Bell, wife of Joshua Bird and both of Generation 3.

• Cohort X5A consists of two samples from descendants of Archibald Bell which have a 13% significance with Cohort 1. There is a good deal of circumstantial evidence that suggests Drusilla's direct or near-direct descent from this man, but it remains undocumented.
• Cohort X5B consists of two samples from descendants of John Bell and Mary Montgomery which also have a 13% significance with Cohort 1. Circumstantial evidence suggests a more distant descent from this man, but that too remains speculative.
• Cohort X5C consists of two samples from descendants of John Bell and Elizabeth Todd which have a 7% significance with Cohort 1, suggesting a relation.
• Cohort X5D consists of a single sample from descendants of William Bell and Sarah Ingram which has a 7% significance with Cohort 1, suggesting a relation.

Generation 4 Spouse

♀ Admixture w/ Dutch "Kwiks"

• ▲Triangulated match▲Bird-3/Bird-5/Kwik-1 on Chr. 5 @ 9.4 cMs

A triangulated match among samples from Cohort 1 and an unrelated sample proves common descent from an unknown MRCA - probably Jacobus Kwik and Francisca van Salis Duck. The source of this DNA is presumed to be Rhoda Schermerhorn, wife of Francis Bird and both of Generation 4.

Sources

1. ↑ Wayne, Debby (2016). Genetic Genealogy Journey: Triangulating Autosomal DNA. National Genealogical Society Magazine.
2. ↑ ^{2.0 2.1} Coop, Ralph P. (2013). The Geography of Recent Genetic Ancestry across Europe. PLOS Biology 11(5):e1001555.
3. ↑ ^{3.0 3.1} Durand EY, Eriksson N, McLean CY. (2014). Reducing pervasive false positive identical-by-descent segments detected by large-scale pedigree analysis. Molecular Biology and Evolution.
4. ↑ Autosomal DNA match thresholds, International Society of Genetic Genealogy Wiki, edited on 17 August 2020.
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. ↑ Tenny, S., Abdelgawad, I. Statistical Significance. [Updated 2022 Nov 21]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan.
7. ↑ Keating, G. (1857). The History of Ireland from the Earliest Period to the English Invasion, p. 726. United States: P. M. Haverty. Google Books.