The Landry Lines in North America
By Ben R. Londeree
The Landry Surname yDNA Project1 has identified three major independent lines of Landrys living in North America. Two lines migrated from France in the 1600s: 1: Guilluame Landry and 2: Rene l’aine (The Elder) and Rene le jeune (The Younger) Landry (cousins). These lines account for most of the Landrys in North America. The third line came from Switzerland in the 1830s: Jean Jacques Landry.
Let me explain briefly the theory behind the use of the yDNA profiles in genealogy. During the conception of males, the father’s y chromosome is passed on pretty much intact to his sons. This process is repeated by his sons who pass this same y chromosome profile to their sons. Therefore if two individuals have the same yDNA profile, they must have a common male ancestor. Recall that I stated that the y chromosome is passed on pretty much intact. Fortunately yDNA chromosomes are pretty stable. Periodically a mutation will occur in one of the markers in the yDNA profile. On average, a mutation will occur on a marker about once in every 500 male births. A common yDNA profile consists of 37 markers so on average there would be a mutation on any marker every 13.5 male births. Therefore after several to many generations slight differences tend to show up in yDNA profiles. The changes are cumulative so that after many generations, the differences between descendants of different lines become greater. Therefore if two males have exactly the same yDNA profile, they have a common male ancestor within a small number of generations. A difference on one marker would mean that their common ancestor probably is more removed. With more differences between them, the common ancestor probably is removed even farther.
In the Landry Surname yDNA Project, individuals with known lineages back to Guillaume Landry, Rene l’aine Landry, and Rene le jeune Landry donated inside the cheek samples to determine their yDNA profiles. Others who did not know their lineages participated as well. Some of the individuals were recruited but others participated because they were curious. The samples were analyzed for each individual’s yDNA profile.
The results showed two distinctly different patterns of profiles and one that did not match any of the others. One cluster of two individuals included the known descendant of Guillaume Landry.
The second cluster of nine individuals included the known descendants of Rene l’aine Landry and Rene le jeune Landry (Acadian Landrys). This clustering is evidence that these two progenitors were related. Stephen White used Catholic Church dispensations for the marriage of two descendants of the two Renes to conclude that if there was a common ancestor of the two Renes, he was not a father or grandfather.2
However, there was a common difference on two markers (representing one mutation) between two sub-clusters of the second cluster. One sub-cluster of two individuals included a known descendant of Rene l’aine Landry. The lineage for the other member of this sub-cluster was known back to 1730. The yDNA results in conjunction with analysis of exiled groups of Acadians enabled us to establish his lineage back to Rene l’aine Landry. The second sub-cluster of seven individuals included two known descendants of Rene le jeune Landry and a third individual whose lineage tentatively is known (out of wedlock conception.)
The one individual with the unique yDNA profile recalls family stories linking him to Switzerland. These stories would link him to Jean Jacques Landry who emigrated from Switzerland in the 1830s. A sample from a known descendant of Jean Jacques Landry would enable us to test this hypothesis.
To date, the Landry Surname yDNA Project has identified three unique Landry lines in North America. Due to the small number of participants in the project, all possible lines may not have been identified. If there are others, they probably arrived more recently and/or there are no living male descendants.
2 White, Stephen A., English Supplement to the Dictionnaire Genealogique des Families Acadienes. Centr d'Etudes Acadienes, Universite de Moncton, Moncton, NB, Canada, pp. 194-5.