TxSGS is now accepting DNA as evidence of parent-child relationships for applicants for heritage certificates (First Families of Texas, and so on) and for the Early Texans DNA Project. This document describes the submission requirements.
In plain words, TxSGS needs a few paragraphs (up to several pages for more complicated cases) describing how the DNA evidence supports a parent-child link in your lineage. This might be a relationship where no supporting document exists or where a document erroneously names a parent (such as when a birth certificate names adoptive and not biological parents) and so on. The narrative you write will be a DNA proof argument explaining in a logical sequence how the documentary and DNA evidence conflict or are consistent with your conclusion about a relationship. DNA testing company match lists, output of DNA tools used, and pertinent documents should be included with the proof argument narrative.
Anyone effectively using DNA as evidence for a genealogical relationship has probably already done this analysis even if it was all done mentally and is not yet written down. Writing it down allows TxSGS DNA Committee members to evaluate your proof argument and attachments to determine whether the relationship claim is credibly supported.
If you already know how to write a proof argument and what is needed to prove a parent-child link with DNA you can skip directly to the Requirements: The Proof Argument Must Include section. If you want guidelines on the process and links to sample proof argument articles then continue to read. A glossary is included at the end of the document for proof and evidence terms; we assume you understand DNA terms if you are using DNA evidence.
Content LinksNote: Inclusion here of any companies, websites, or tool does not constitute endorsement. DNA test takers should investigate any company, website, or tool and the policies, terms of service, and user agreements before using any such service or tool.
DNA is treated like any other genealogical evidence in a lineage application. The requirements below may seem daunting, but TxSGS is only asking submitters to explain how the DNA evidence supports the genealogical conclusion about a relationship. Adherence to these requirements should lead to more successful applications using DNA evidence.
DNA is considered an accepted type of evidence by almost all genealogists.1 Genealogical use of DNA has been taught at genealogy conferences since about 2000, has been taught in institutes in the US since 2014, and has been defined in Genealogy Standards2 since early 2019. Online resources explaining and demonstrating the use of DNA evidence are readily available.3 For several years now, some lineage societies have accepted DNA evidence. However, many of those societies place restrictive rules on using DNA.
Some applicants for heritage certificates (First Families of Texas and others) are using DNA evidence to support a biological relationship to a qualifying ancestor, as are some applicants to the Early Texans DNA Project.
TxSGS now allows DNA evidence for lineage proofs; however, the evidence must be presented following the requirements and recommendations listed below. This follows practices accepted by the genealogical community.
DNA evidence for parent-child links is allowed in applications submitted to TxSGS for heritage certificates and for the Early Texans DNA Project. The evidence must be presented in a logical narrative or proof argument.
The DNA evidence analysis may contradict the traditional documentary evidence used for genealogy. Even official government documents such as birth certificates may contain incorrect information, possibly from an informant who did not know the truth, had reason to hide the truth, a scribe who heard or wrote the wrong phrase or word, or as when a birth certificate names only the adoptive parents. While DNA evidence does not lie, it can be misinterpreted—just as evidence from a probate file or deed can be misinterpreted. For correct interpretation the DNA evidence must be correlated with documentary evidence. Both the DNA and documentary research must be sufficiently thorough to reduce the chance of future findings contradicting the current interpretation.
A written narrative, or proof argument, should correlate the documentary and DNA evidence in a logical manner and explain the reasoning for acceptance of the DNA evidence. The proof argument should be detailed enough to allow TxSGS to evaluate the assertions and the evidence. Source documents and printouts from DNA testing companies should be attached. These can be assigned document numbers for easy reference in the proof argument. This will assist TxSGS in following the logic and evaluating the validity of the assertion. A scatter-shot collection of printouts would require an inordinate number of hours for evaluation. It might also leave open the possibility of TxSGS's evaluation focusing on something other than the key element an applicant used to determine an ancestral line.
An applicant might need to consult example proof arguments demonstrating best practices or, alternately, consult a professional with experience in interpreting and writing about DNA. Good examples of proof arguments are listed below in "Sample Proof Arguments."
The submitted proof argument will be evaluated by a minimum of two persons experienced in DNA analysis.
It is impossible to make a rule about a minimum test level that will be adequate for all situations. Some low level tests or testing a single person can provide evidence against an assertion (to disprove) in any situation or to support an assertion with a rare name or haplogroup. Higher level tests (more Y-DNA STR markers or a full mtDNA sequence) are needed in some situations and with common names. The following general guidelines are provided; however, the real standard of measurement is based on Genealogy Standards and best practices.4
A Y-DNA STR test for fewer than 37 markers is best used as evidence against an assertion. For several years, the minimum level Y-DNA STR test recommended was 37 markers. Most experienced researchers now recommend a minimum of 67 markers. Some now recommend a Y-DNA SNP test such as Big Y-500 or Big Y-700, Y-Elite, or similar information from a test such as a Whole Genome Sequence (WGS).
Whenever possible, it is better to use at least 67 or 111 Y-DNA STR markers. Exact matches are not required. However, a descendant chart should show the likely locations where any existing mutations could have occurred. See "Attachment C: Charts With Likely Mutation Occurrences." Information from surname projects are likely to be helpful in explaining where mutations may have occurred.
An mtDNA test that does not include the full mitochondrial sequence is best used as evidence against an assertion. Unless the mtDNA haplogroup is a very rare type, even a full mtDNA sequence is only "consistent with" or "does not contradict" an assertion. This is because mtDNA mutations happen less frequently resulting in the same exact sequence being passed down for hundreds or thousands of years. A person can share a full mtDNA exact match with another even when their common ancestor is no closer than two thousand years ago, for example.
Shared atDNA amounts between two test takers of a presumed relationship should be consistent with statistical probabilities,5 or better yet, the reported amounts from the Shared cM Project.6
The Shared cM Project findings are automated and freely available at the DNA Painter website (https://dnapainter.com/tools/sharedcmv4).7 The output shows the probabilities of multiple relationships there might be between two test takers sharing a specific amount of DNA. Where multiple possible relationships are shown, the proof argument should explain why relationships other than the hypothesized relationship are improbable (ruled out).
Shared match lists and clustering tools may support claims of a common ancestor. Useful DNA evidence may also be found with chromosome maps (such as those created on DNA Painter's main pages or tools like GEDmatch) and triangulated DNA segment maps (such as those provided by GEDmatch and MyHeritage). Shared Ancestor Hints and ThruLines at Ancestry.com, Theories of Relativity at MyHeritage.com, and similar clues displayed by testing companies and other analysis tools must be treated as clues supplemented by documentation that supports the hypothesis.
Only atDNA segments longer than 15 cM should be used in a proof argument unless short segment can be shown to be a portion of a longer segment shared with a relative on the same line or the short segment can be "walked back" through each generation of ancestors to the common ancestor between two test takers.8 There are multiple means of walking back a DNA segment to a specific ancestral line.
For X-DNA, an understanding of the unique inheritance pattern of the X chromosome and its application in this case must be incorporated into the proof argument. Only X-DNA segments longer than 20 cM will be considered without the inclusion of substantial supporting evidence.
A close relationship should be much simpler to write about than many of the more distant relationships covered in some National Genealogical Society Quarterly (NGSQ) articles incorporating DNA evidence. If an applicant is not an NGS member,9 most genealogy libraries carry the NGSQ, which has many examples using DNA in recent issues. Many libraries in Texas and elsewhere carry Stirpes, the Journal of the Texas State Genealogical Society. There are also many blog posts with examples of DNA analysis included in a proof argument.10 Using recent articles is recommended as the best practices in using DNA have evolved with time and experience.
See also "DNA Resources" in the BCG Learning Center (https://bcgcertification.org/learning/dna-resources/).
Articles can also be found in other scholarly and peer-reviewed journals. Be careful using articles printed in journals that do not use peer review. Some such articles may be excellent, but some may have undergone less rigorous investigation before being published and will not demonstrate best practices.
For sample proof arguments see these articles paying special attention to the DNA sections of the articles:
Note: Some of these articles were written prior to publication of the 2019 edition of Genealogy Standards that added specific requirements for DNA analysis. Every article may not meet all of the current standards, but all have some good ideas on how to write about DNA analysis.
1. Widely accepted abbreviations for DNA types are used throughout this document: Y-DNA, X-DNA, mitochondrial DNA (mtDNA), and autosomal DNA (atDNA). These should be understood by anyone using DNA to prove a genealogical relationship.
2. Board for Certification of Genealogists (BCG), Genealogy Standards, 2nd ed. (Nashville, Tenn.: Ancestry.com Imprint, Turner Publ., 2019).
3. "DNA Resources," BCG Learning Center (https://bcgcertification.org/learning/dna-resources/).
4. BCG, Genealogy Standards.
5. "Autosomal DNA statistics," ISOGG Wiki (https://isogg.org/wiki/Autosomal_DNA_statistics).
6. Blaine T. Bettinger, "Shared cM Project," The Genetic Genealogist (https://thegeneticgenealogist.com/). Search the blog posts for the most recent update to the project such as the March 2020 update at https://thegeneticgenealogist.com/2020/03/27/version-4-0-march-2020-update-to-the-shared-cm-project/. The March 2020 version of the PDF file is at https://thegeneticgenealogist.com/wp-content/uploads/2020/03/Shared-cM-Project-Version-4.pdf. The project charts are periodically updated.
7. Jonny Perl and Blaine T. Bettinger, "The Shared cM Project 4.0 tool v4," DNA Painter (https://dnapainter.com/tools/sharedcmv4).
8. One method of walking back an ancestor can be found in Jim Bartlett, "Walking the Ancestor Back," segment-ology blog, 4 January 2017 (https://segmentology.org/2017/01/04/walking-the-ancestor-back/).
9. (US) National Genealogical Society (https://www.ngsgenealogy.org/).
10. Jim Bartlett, segment-ology blog (https://segmentology.org/). Roberta Estes, DNA Explained (http://dna-explained.com/). Debbie Parker Wayne, Deb's Delvings in Genealogy (http://debsdelvings.blogspot.com/). See also, "Genetic genealogy blogs," ISOGG Wiki (https://isogg.org/wiki/Genetic_genealogy_blogs).