Griswold DNA Project: Griswold Mystery Solved by Big Y DNA Testing

By Becky Griswold and Coralee Griswold reprinted from our October 2023 Bulletin

Last year we introduced you to the Big Y DNA test and stated it is a game changer. We also mentioned it could help solve some of our Griswold genealogical mysteries.

This year we have an example of how the Big Y test solved just such a mystery which was still unsolved even after 70 years of searching for the answer! It is the kind of mystery that could only have been solved by using DNA and the Big Y test specifically.

Please Note: All living individuals named in this article have given permission to use their names and information.

To recap, the first Y-DNA test offered by Family Tree DNA (FTDNA) was the Y-STR test. This test tells you that you and your Y-DNA matches descend from the same man. This information was groundbreaking for many years, but now, that is the extent of the Y-STR test’s usefulness.

Regarding your Griswold ancestry, the Y-STR test may confirm that you descend from either Edward Griswold or Michael Griswold. Although he has male descendants, we have not yet found a living male descendant of Matthew to take the Big Y test.

Thankfully, the Edward Griswold descendants have various Y-STR mutations that allow us to distinguish between the DNA signatures of the two men. However, for those testers who have a gap in their paper trail, Y-STR DNA is simply a guide, it is not 100% foolproof.

Why is the Big Y test a game changer? In addition to telling us THAT two or more matches descend from the same man, more importantly, it tells us HOW those matches are related to each other. Big Y uses a mutation called a SNP. A SNP will occur in one man and one man only. Once we know which Griswold man got a SNP mutation, we know that ALL of his male descendants also got that SNP. Then, when a living male descendant of his takes the Big Y test, the SNP of that Griswold ancestor is revealed.

Just last month (September 2023), we successfully used the Big Y test to solve a Griswold family mystery.

In August 2022 Allen Codding contacted Coralee Griswold, GFA Genealogist, with a mystery. He knew he was a Griswold through his 4 times great-grandmother, Mary Griswold, who was the daughter of Isaac Griswold (GFA #786/1322) and Anne Irwin. Allen had not only researched this line, but had also taken the Family Finder (Autosomal DNA) test and had matches to other descendants of this couple. Mary Griswold married Robert T. Codding. Their daughter, Ellen Codding, had a son out of wedlock whom she named Martin Van Codding. Martin’s father was unknown as Ellen had given her son her surname instead of the surname of his biological father. Allen told us that his family had been searching for Martin Van Codding’s father since 1950.

Allen had recently taken the Y-STR DNA test to see if he could figure out who Martin V. Codding’s father was. The test showed that he matched men with the surname of Griswold. We knew the surname would not be Codding since this was his mother’s surname. But none of us could have predicted what surname his Y-DNA would match. We were all very surprised when it turned out to be Griswold.

Coralee advised Allen to join the Griswold DNA project, which he did. With his Y-STR test results showing a direct paternal connection to a Griswold male, DNA had proven a Griswold connection through two different lines. Now the task was to figure out what his other Griswold line was. Coralee and I surmised he was probably an Edward descendant because he had a Y-STR mutation also found in the Y-DNA of Coralee’s father as well as five other Edward descendants. This mutation was not present in the Y-DNA of any of the Michael Griswold descendants.

Coralee and I had been discussing the Big Y test, but she was still on the fence. I explained how it had helped me solve a longstanding personal family mystery. I also reminded her of all of the Griswold mysteries we were faced with. Through those conversations (truth be told she probably got tired of me bugging her) she decided to upgrade her father’s Y-STR test to Big Y. Although Coralee’s father, Lee Griswold, had passed away in 2014, he had given her beneficiary rights to his DNA. FTDNA has each tester’s DNA in storage so they were able to run the Big Y test on Lee’s stored DNA. Three days later, Allen Codding also decided to upgrade his Y-STR test to Big Y.

The Big Y test takes six to eight weeks to process. By October 2022 both men’s Big Y results were in. Lee and Allen had gotten the same exact SNP mutation, R-FTD7233. When two men get the same SNP mutation it means they both descend from the same man. Remember, once a man gets a SNP mutation in his Y-DNA, he passes it down to all of his direct line male descendants.

At that time, we did not have the tools to predict which ancestor had gotten that SNP. Since Lee was the only one whose line was confirmed, we “guessed” that either Lee’s great-grandfather, Oscar Griswold [GFA #1857/2814] or his great-great-grandfather, Isaac Griswold [GFA #786/1322] had gotten the mutation in his Y-DNA. But in all honesty, it could have been a man further back in Lee’s ancestry as well.

Luckily, around this same time, FTDNA debuted a new feature for Big Y test takers called the Time Tree. The Time Tree feature uses an algorithm to estimate the birth year of the person who got each SNP mutation. Unfortunately, the Time Tree feature was still in its infancy and not very reliable.

Fast Forward to June 2023.  FTDNA had fine-tuned the Time Tree feature. I took another look at the Time Tree for SNP R-FTD7233.  The birth year of the person who got this SNP was estimated to be 1831. That narrowed down considerably the choices of who got this SNP. Now we were only considering two men. Either Lee’s great-grandfather, Oscar Griswold [GFA #1857/2814] or his grandfather, Isaac Griswold [GFA #3429/4592] had gotten this SNP mutation. Oscar was born in 1812 and Isaac was born in 1845. So, the Time Tree estimated birth year of 1831 fell right between Oscar’s and Isaac’s birth years.

I realized we could now solve Allen Codding’s mystery, but needed one more Griswold Big Y tester. This new person had to be a descendant of one of Oscar’s other sons (they could not be from Isaac). If the new tester got the same SNP as Lee and Allen, Oscar would be Martin’s father. If he got a different SNP, then Isaac would be the father. The important take away here is we have to have descendants whose lineage is known take the Big Y test. Their results are vital to “proving” those of unknown lineage.

I asked Coralee to check for living male descendants of Oscar’s other sons for potential Big Y testers. She sent emails to the list and her 3rd cousin Bob Griswold volunteered to take the test. Bob descends from Oscar’s son, Chauncey W. Griswold [GFA #3437/4599].

Bob’s Big Y test was ordered in June 2023 and we got the results back in September. After analyzing the results, I informed Coralee, Allen and Bob that Bob had gotten the exact same SNP as Lee and Allen had, SNP R-FTD7233. That meant Oscar Griswold, Lee’s great-grandfather was the father of Martin Van Codding. Allen Codding’s family mystery was finally solved after more than 70 years of research, thanks to Big Y and generous participants!

Additionally, now that we had three Big Y testers who got the same SNP, FTDNA’s Time Tree algorithm could more accurately estimate the birth year of the person who got that SNP. The Time Tree now estimated the person with SNP R-FTD7233 was born about 1780. Remember Oscar was born in 1812, 32 years off the estimated birth year. So, it was unlikely that Oscar got the SNP. Next, we looked at the birth year for Oscar’s father, Isaac Griswold [GFA #786/1322]. Isaac was born in 1781. That is very close to the Time Tree estimated birth year of 1780. Now we could conclude with certainty that Isaac Griswold [GFA #786/1322] is the man who got the SNP mutation, R-FTD7233, in his Y-DNA.

Thanks to the Big Y test, Allen Codding’s mystery was solved! Moving forward, any new testers who get SNP R-FTD7233 are 100% descendants of Isaac Griswold [GFA #786/1322], whether they have traced their line back to him or not.

Participating in the Griswold DNA Project by taking the Big Y test is a huge advancement to our study of Griswold DNA.

Please consider sponsoring a Big Y DNA test to assist those who would like to take the test but may not feel it is affordable at this time. You might gain a whole new limb to your tree and help solve a Griswold mystery!

Male Griswolds who have already taken the Y-STR test, consider upgrading your test to Big Y.

Ladies, if you can find a living male Griswold from your line, ask them to take the Big Y DNA test for you.

Family Tree DNA will have a sale on all of their tests starting in November and running through the end of the year.

If you have any questions about the Big Y test or DNA questions in general, please email Becky at  Click to learn more about the Griswold DNA project.

This relationship chart shown should help readers better grasp the familial relationships involved in this mystery: