AUTOSOMAL DNA AND GENEALOGY:
HOW CAN DNA AND TRIANGULATION BE USED
TO IDENTIFY, EVALUATE AND PRESENT
CONCLUSIONS OF RELATEDNESS?
Author(s): Thad Thomas, MSc
Originally Published: Vol 9, Num 1 (Fall 2021)
Reference Number: 91.005
Note: The full article is too long to reproduce here but the Abstract and Table of Contents are provided below. For the full article please use the View PDF link.
Abstract
Table of Contents
Abstract
DNA genotyping allows consumers to examine their genetic heritage, including (within limits) a record of their ancestry. Computer algorithms can associate genotyped individuals who appear to share a genetic past, but appearances cannot be the basis for declaring genealogical relationships. While parent/child relationships can be established with certainty, other genealogical relationships can only be estimated—even in cases where a genetic relationship is sure to exist. How, then, can autosomal DNA (atDNA) be used to reveal, confirm, or even prove genealogical relationships?
This text presents a methodology for identifying, evaluating, and presenting a conclusion of relatedness utilizing atDNA. This methodology fits firmly within the framework of the genealogical research process, enabling atDNA to be used in proof arguments about relationships through the processes of question asking, information gathering, hypothesis testing, conclusion accepting, and proof explained.
The genetic genealogical community has not been definitive about acceptance criteria for atDNA-based conclusions (i.e., required elements, standards of evaluation, etc.), and more especially triangulated conclusions. It is the author’s opinion that triangulation ought to be central to most genetic genealogical proof arguments, yet the literature explaining triangulation fails to make plain the reasons why triangulation is effective. These deficiencies can be addressed by decomposing triangulation into its fundamental building blocks and re-presenting it in the context of the genealogical research process.
This text focuses particularly on how hypothesis testing is used to determine strengths and weaknesses of atDNA-based conclusions. This discussion includes important heuristics that help the genetic genealogist understand the capabilities and limits that accompany this biotechnical genealogical record.
Table of Contents
Abstract …………………………………………………………………………………………… 3
Contents ………………………………………………………………………………………….. 4
List of Figures ………………………………………………………………………………… 10
Definitions ……………………………………………………………………………………… 14
Key for Lineage Diagrams……………………………………………………………….. 18
Introduction……………………………………………………………………………………. 19
Genotyping…………………………………………………………………………………………….19
Genetics and Genomics………………………………………………………………………….20
Literature ……………………………………………………………………………………….. 25
Personal Genomics ………………………………………………………………………………..25
DNA Inheritance……………………………………………………………………………………..25
Success Stories……………………………………………………………………………………..26
Proof ……………………………………………………………………………………………………..26
Social Concerns……………………………………………………………………………………..27
Quantitative Analysis ……………………………………………………………………………..28
Triangulation………………………………………………………………………………………….29
Evaluating Matching Segments……………………………………………………………….30
Phasing………………………………………………………………………………………………….31
Chromosome Mapping……………………………………………………………………………32
Research Process…………………………………………………………………………… 33
Methodology…………………………………………………………………………………… 36
Genealogical Research Principles and Practice……………………………………….36
Question Asking …………………………………………………………………………………….38
Information Gathering…………………………………………………………………………….38
Core Sources ……………………………………………………………………………………….38
Core Information …………………………………………………………………………………..39
Genotypes………………………………………………………………………………………………….. 39
IBD vs. IBS vs. IBC ………………………………………………………………………………….. 40
Match Lists ……………………………………………………………………………………………… 42
Ethnicity Estimates…………………………………………………………………………………… 44
Lineages…………………………………………………………………………………………………….. 45
Developing a Research Plan…………………………………………………………………..46
Identifying Genotype Sources ……………………………………………………………………….. 46
Recruiting Sources………………………………………………………………………………………. 48
Preparing Your Own Family Tree…………………………………………………………………… 48
Information Gathering Is On-going…………………………………………………………..49
Hypothesis Testing…………………………………………………………………………………49
Tentative Answers…………………………………………………………………………………49
Evidence from Quantitative Information ………………………………………………………….. 49
A Note About Quantities……………………………………………………………………………….. 52
Evidence from Triangulation………………………………………………………………………….. 53
An Axiom and a Theorem……………………………………………………………………………… 53
The Fundamental Building Block of Triangulation…………………………………………….. 54
Identifying Triangulation Building Blocks…………………………………………………………. 55
Isolating � ……………………………………………………………………………………………… 55
Isolating �……………………………………………………………………………………………….. 56
What’s Next?…………………………………………………………………………………………… 57
A Concrete Example ………………………………………………………………………………… 57
Correlating the Instances of � ……………………………………………………………………….. 59
Correlating �………………………………………………………………………………………….. 60
Correlating � …………………………………………………………………………………………… 62
Triangulation in Terms of � …………………………………………………………………………… 62
Testing ………………………………………………………………………………………………..63
Tests of Analysis…………………………………………………………………………………..63
Quantitative Considerations ………………………………………………………………………….. 63
Matching Segment Size ……………………………………………………………………………. 64
Total Shared IBD……………………………………………………………………………………… 66
Evaluating Compiled Genealogies …………………………………………………………………. 69
Tests of Correlation……………………………………………………………………………….71
Independence vs. Relatedness……………………………………………………………………… 71
Testing the IBD Assertion……………………………………………………………………………… 73
Phased Matching……………………………………………………………………………………… 73
Generational Matching ……………………………………………………………………………… 74
Intermediate Common Ancestors……………………………………………………………….. 74
Close Relative Matching……………………………………………………………………………. 76
Match Stability …………………………………………………………………………………………. 77
Chromosome Map Correlation …………………………………………………………………… 78
Excessive Matching………………………………………………………………………………….. 79
Solution Predicts Relationships……………………………………………………………………… 82
Common Ancestor Uniqueness……………………………………………………………………… 82
Looking Forward …………………………………………………………………………………..84
Conclusion Accepting…………………………………………………………………………….84
Proof Explained ……………………………………………………………………………………..85
Summary………………………………………………………………………………………… 87
Bibliography…………………………………………………………………………………… 88
Primary Sources …………………………………………………………………………………….88
Secondary Sources ………………………………………………………………………………..96
Appendix A: Finding an Adoptee’s Biological Family…………………….. 109
Appendix B: Triangulation for GT999 on Chr1 from 159M to 167M …. 111
Tests of Analysis ………………………………………………………………………………….112
Matching Segment Size ……………………………………………………………………….112
Total Shared IBD…………………………………………………………………………………113
Tests of Correlation………………………………………………………………………………114
Independence …………………………………………………………………………………….114
Excessive Matching …………………………………………………………………………….115
Chromosome Map Correlation………………………………………………………………115
Intermediate Common Ancestors…………………………………………………………..115
Phased Matching ………………………………………………………………………………..115
Generational Matching…………………………………………………………………………115
Close Relative Matching ………………………………………………………………………116
Match Stability…………………………………………………………………………………….116
� (1 of 2)…………………………………………………………………………………………….116
Common Ancestor Uniqueness……………………………………………………………………. 116
Conclusion for � (1 of 2)……………………………………………………………………………… 117
� (2 of 2)…………………………………………………………………………………………….117
Common Ancestor Uniqueness……………………………………………………………………. 117
Conclusion for � (2 of 2)……………………………………………………………………………… 117
Conclusion Accepting…………………………………………………………………………..118
Appendix C: Triangulation for GT999 on Chr4 from 187M to 191M …. 119
Tests of Analysis ………………………………………………………………………………….119
Matching Segment Size ……………………………………………………………………….119
Total Shared IBD…………………………………………………………………………………119
Tests of Correlation………………………………………………………………………………120
Independence …………………………………………………………………………………….120
Excessive Matching …………………………………………………………………………….120
Chromosome Map Correlation………………………………………………………………120
Intermediate Common Ancestors…………………………………………………………..120
Phased Matching ………………………………………………………………………………..120
� (1 of 3)…………………………………………………………………………………………….121
Generational Matching ……………………………………………………………………………….. 121
Close Relative Matching……………………………………………………………………………… 121
Match Stability…………………………………………………………………………………………… 121
Common Ancestor Uniqueness……………………………………………………………………. 122
Conclusion for � (1 of 3)……………………………………………………………………………… 122
� (2 of 3)…………………………………………………………………………………………….122
Generational Matching ……………………………………………………………………………….. 123
Close Relative Matching……………………………………………………………………………… 123
Match Stability…………………………………………………………………………………………… 123
Common Ancestor Uniqueness……………………………………………………………………. 123
Conclusion for � (2 of 3)……………………………………………………………………………… 124
� (3 of 3)…………………………………………………………………………………………….124
Common Ancestor Uniqueness……………………………………………………………………. 124
Generational Matching ……………………………………………………………………………….. 124
Close Relative Matching……………………………………………………………………………… 124
Conclusion for � (3 of 3)……………………………………………………………………………… 125
Other Considerations……………………………………………………………………………125
Conclusion Accepting…………………………………………………………………………..125
Appendix D: Triangulation for GT611 on Chr4 from 177M to 191M …. 126
Tests of Analysis ………………………………………………………………………………….128
Matching Segment Size ……………………………………………………………………….128
Total Shared IBD…………………………………………………………………………………128
Tests of Correlation………………………………………………………………………………129
Independence …………………………………………………………………………………….129
Excessive Matching …………………………………………………………………………….129
Chromosome Map Correlation………………………………………………………………130
Intermediate Common Ancestors…………………………………………………………..130
Phased Matching ………………………………………………………………………………..130
Generational Matching…………………………………………………………………………130
Close Relative Matching ………………………………………………………………………130
Match Stability…………………………………………………………………………………….130
� (1 of 2)…………………………………………………………………………………………….131
Common Ancestor Uniqueness……………………………………………………………………. 131
Conclusion for � (1 of 2)……………………………………………………………………………… 132
� (2 of 2)…………………………………………………………………………………………….132
Common Ancestor Uniqueness……………………………………………………………………. 132
Conclusion for � (2 of 2)……………………………………………………………………………… 132
Other Considerations……………………………………………………………………………133
Conclusion Accepting…………………………………………………………………………..133
Appendix E: An X Chromosome Match …………………………………………. 134
Appendix F: Triangulation for GT999 on Chr1 from 180M to 195M….. 136
Proposed Common Ancestor………………………………………………………………..137
Triangulation Evaluation……………………………………………………………………….138
Tests of Analysis…………………………………………………………………………………138
Matching Segment Size ……………………………………………………………………………… 138
Total Shared IBD……………………………………………………………………………………….. 138
Tests of Correlation……………………………………………………………………………..139
Independence……………………………………………………………………………………………. 139
Excessive Matching……………………………………………………………………………………. 139
Chromosome Map Correlation …………………………………………………………………….. 139
Intermediate Common Ancestors…………………………………………………………………. 140
Phased Matching……………………………………………………………………………………….. 140
Generational Matching ……………………………………………………………………………….. 140
Close Relative Matching……………………………………………………………………………… 140
Match Stability…………………………………………………………………………………………… 140
� (1 of 2)…………………………………………………………………………………………………… 141
Common Ancestor Uniqueness………………………………………………………………… 141
Conclusion for � (1 of 2)………………………………………………………………………….. 142
� (2 of 2)…………………………………………………………………………………………………… 142
Common Ancestor Uniqueness………………………………………………………………… 142
Conclusion for � (2 of 2)………………………………………………………………………….. 143
Solution Predicts Relationships……………………………………………………………………. 143
Other Considerations …………………………………………………………………………..143
Conclusion Accepting…………………………………………………………………………..144
The SHAW Connection………………………………………………………………………….144
Daniel SHAW Identified………………………………………………………………………..146
The Union…………………………………………………………………………………………..146
NY 1815 Port Arrivals…………………………………………………………………………..148
Daniel SHAW ……………………………………………………………………………………..148
Olive SHAW ……………………………………………………………………………………….148
Elkanah SHAW …………………………………………………………………………………..149
Daniel SHAW Jr. …………………………………………………………………………………149
Waitstill SHAW……………………………………………………………………………………149
Salmon SHAW ……………………………………………………………………………………150
Hazael SHAW …………………………………………………………………………………….151
Elizabeth SHAW………………………………………………………………………………….151
Susannah SHAW ………………………………………………………………………………..152
Arrival Record Informant ………………………………………………………………………153
Arrival Record Conclusion…………………………………………………………………….154
Being a SHAW in Potsdam …………………………………………………………………..154
Brick Wall Crumbling ……………………………………………………………………………154
