Exploring Y-DNA Inheritance- A Case Study with Great-grandfather John Weaver’s Family Tree
Y-DNA Discussion
While females carry XX pairs, males carry XY chromosome pairs. They inherit the X chromosome from their mother and the Y chromosome from their father. Thus, Y-DNA testing is particularly administered to males. The Y chromosome is inherited almost unaltered; thus, it remains almost the same for my generations (Bettinger and Wayne, 2016). Y-DNA testing utilizes Short Tandem Repeats (STRs) and Short Nucleotide Polymorphisms (SNPs), which are primarily used to characterize individual haplotypes and mark haplogroups, respectively.
Y-DNA Inheritance
Based on the scenario presented in the chart, individuals 3, 5, 6, and 7 potentially trace their Y-DNA back to their great-grandfather, John Weaver. The son marked A only has a daughter; therefore, he cannot pass down his Y chromosome DNA to the following generations. Hence, individuals marked 1 and 2 do not carry John’s Y-DNA. Also, females do not inherit Y chromosomes; thus, Individual 4 does not carry John’s Y-DNA.
111-marker Test
Genetic distances can be described by the number of mutations responsible for differences between STRs of the test takers under comparison. It is given by the number of observed differences between these markers (Tëtushkin, 2011). After taking a 111-marker Y-DNA test, Individuals 3 and 6 revealed a genetic distance of 0. This indicates that they inherited similar Y-DNA with no mutations, thus no observable differences between their STR markers. It also suggests that they share an identical paternal ancestor.
23andMe Test
23andMe test taken shows that Individuals 3, 5, and 6 belong to a similar haplogroup, R1b, while 7 belong to J1c2a, a different group. This indicates that 7 inherited Y-DNA had undergone mutations, which explains the difference in his STR marker. Individuals 3, 5, and 6 portray a haplogroup match, suggesting that they are from a common paternal ancestor.
In conclusion, Y-DNA testing has proven to be an essential tool in molecular genealogy. Following tests such as 111-marker Y-DNA and 23andMe tests, it is used to trace male individuals’ Y-DNA to their patrilineal ancestors of many generations ago. In this case, Individuals 3, 5, and 6 potentially carry John’s Y-DNA.
References
Bettinger, B., & Wayne, D. (2016). Genetic Genealogy in Practice. National Genealogical Society.
Tëtushkin, E. (2011). Genetic genealogy: History and methodology. Russian Journal of Genetics, 47(5), 507-520. doi: 10.1134/
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Question 
In this activity, you will answer questions about a Y-DNA scenario, which will analyze your understanding of the unique inheritance of the Y chromosome and how Y-DNA is transmitted through a family tree.
Great-grandfather John Weaver, denoted by purple in the descendant chart provided, has taken a Y-STR DNA test. His results suggest that his Y-DNA haplogroup is R1b1a2a1c1a. You’ve identified all seven great-grandchildren of John Weaver and his wife and numbered them 1 through 7.
Exploring Y-DNA Inheritance- A Case Study with Great-grandfather John Weaver’s Family Tree
Based on your understanding of Y-DNA and the descendant chart, answer the following questions:
Based on the chart, which of John Weaver’s great-grandchildren trace their Y-DNA back to John?
Individuals #3 and 6 each take a 111-marker Y-DNA test, and the genetic distance is 0. What could explain this result?
Individuals #3, 5, 6, and 7 purchase 23andMe tests. According to the test results, the Y-DNA of individuals #3, 5, and 6 belong to haplogroup R1b. Individual #7 belongs to haplogroup J1c2a. What could explain this result?
Your assignment is due by the end of the module, Thursday at 11:59 PM EST. Be sure to use proper APA or Chicago-style formatting. For assistance with proper formatting,