GENE201 Module 2 M2A3: The X-DNA Inheritance Project
This project evaluates your understanding of the unique inheritance of X-DNA.
Five generations of MaryEllen Sullivan’s family tree are provided in the pedigree chart. MaryEllen decides to take a DNA test that examines her X-DNA. When she gets the results, she discovers that she shares a large piece of X-DNA with a person named Georgia Thomas. When MaryEllen and Georgia compare their family trees, the only overlap they identify is the surname “BENTLEY.” MaryEllen has a Corrine Bentley in her family tree, and Georgia has a Susannah Bentley in her family tree. Unfortunately, neither MaryEllen nor Georgia has any information about Corrine Bentley or Susannah Bentley’s parents or other ancestry.
Based on your understanding of X-DNA and the pedigree chart, answer the following questions:
Could Corrine Bentley be the source of the segment of X-DNA that MaryEllen shares with Georgia? Why or why not?
Assume that the shared surname is “LEWIS,” and that Georgia has an ancestor named Charles Lewis. Could MaryEllen’s ancestor Polly Lewis be the source of the segment of X-DNA that MaryEllen shares with Georgia? Why or why not?
Of the 16 great-great-grandparents shown in the pedigree chart, how many could have contributed X-DNA to MaryEllen?