CGL Genetic Genealogy 2 — Questions and Answers
Question 1: What is 'chromosome painting' in genetic genealogy?
- A technique to identify mutations in specific chromosomes
- A visual representation showing which ancestral populations or ancestors contributed to specific chromosome segments (Correct answer)
- A method for comparing ethnicity compositions between relatives
- A process for identifying recombination hotspots
Correct answer: A visual representation showing which ancestral populations or ancestors contributed to specific chromosome segments
Chromosome painting assigns colors to chromosomal segments to visually indicate which ancestral population or specific ancestor contributed each portion of an individual's DNA.
Question 2: If two of your DNA matches share DNA with you but do not share DNA with each other, what does this most likely indicate?
- They are on the same side of your family
- They are on opposite sides of your family (maternal vs. paternal) (Correct answer)
- Both matches are false positives
- There is a testing error in the database
Correct answer: They are on opposite sides of your family (maternal vs. paternal)
When two matches share DNA with you but not with each other, they most likely descend from different family lines — one maternal and one paternal.
Question 3: What is 'triangulation' in genetic genealogy?
- Testing three generations of a family to build a pedigree
- Confirming a segment is IBD when three or more matches share it at the same chromosomal location with each other (Correct answer)
- Using three different DNA testing companies to verify results
- A technique for resolving conflicting documentary and DNA evidence
Correct answer: Confirming a segment is IBD when three or more matches share it at the same chromosomal location with each other
Triangulation confirms that a DNA segment is truly identical by descent when three or more individuals all share that same segment with one another on the same chromosome.
Question 4: What does 'phasing' refer to in DNA analysis?
- Converting raw DNA data into a usable file format
- Separating an individual's maternal and paternal chromosomal contributions (Correct answer)
- Comparing DNA results across different testing platforms
- Identifying recombination events within a family lineage
Correct answer: Separating an individual's maternal and paternal chromosomal contributions
Phasing is the analytical process of determining which DNA segments came from each parent, effectively separating chromosomes into their maternal and paternal components.
Question 5: A DNA match shares approximately 1,800 cM with you. Which relationship category does this amount most likely represent?
- First cousin
- Half-sibling, grandparent, or aunt/uncle (Correct answer)
- Second cousin
- Third cousin once removed
Correct answer: Half-sibling, grandparent, or aunt/uncle
Approximately 1,800 cM is consistent with a close relationship such as a half-sibling, grandparent, grandchild, aunt, or uncle, which typically range from about 1,300–2,300 cM.
Question 6: What is the primary purpose of the 'Shared Matches' or 'In Common With' feature available on DNA testing platforms?
- To find people who share the same surname in their family tree
- To identify which of your matches are also matched to a specific relative, helping assign them to a family branch (Correct answer)
- To compare ethnicity estimates between two users
- To track family tree connections across multiple databases simultaneously
Correct answer: To identify which of your matches are also matched to a specific relative, helping assign them to a family branch
The Shared Matches feature shows which of your DNA matches are also matched to a selected person, helping genealogists determine which family branch an unknown match belongs to.
Question 7: Which type of DNA is most useful for tracing a direct matrilineal line (mother's mother's mother's...)?
- Y-DNA
- Autosomal DNA (atDNA)
- Mitochondrial DNA (mtDNA) (Correct answer)
- X-DNA
Correct answer: Mitochondrial DNA (mtDNA)
Mitochondrial DNA (mtDNA) is passed essentially unchanged from a mother to all her children and is the definitive test for tracing the direct matrilineal line.
CGL Genetic Genealogy 2
What is 'chromosome painting' in genetic genealogy?