CGL Genetic Genealogy 1 — Questions and Answers
Question 1: Which type of DNA test traces direct patrilineal ancestry by following the Y chromosome?
- mtDNA test
- Y-DNA test (Correct answer)
- Autosomal DNA test
- X-DNA test
Correct answer: Y-DNA test
Y-DNA is passed from father to son with minimal change across generations, making it ideal for tracing the direct patrilineal line.
Question 2: What unit is used to measure the length of shared DNA segments between two individuals in genetic genealogy?
- Base pairs
- Alleles
- Centimorgans (cM) (Correct answer)
- Haplogroups
Correct answer: Centimorgans (cM)
Centimorgans (cM) measure the genetic distance of shared DNA segments and are used to estimate the relationship between two individuals.
Question 3: Which DNA test is most useful for finding relatives across ALL ancestral lines within approximately 5–6 generations?
- Y-DNA
- mtDNA
- Autosomal DNA (atDNA) (Correct answer)
- X-DNA
Correct answer: Autosomal DNA (atDNA)
Autosomal DNA (atDNA) tests all 22 pairs of autosomes and can detect relatives from every branch of the family tree, typically within 5–6 generations.
Question 4: What does 'endogamy' mean in the context of genetic genealogy?
- A DNA mutation that skips generations
- The practice of marrying within a small community, causing elevated DNA sharing among members (Correct answer)
- The process of comparing DNA across multiple databases
- A method for phasing maternal and paternal DNA segments
Correct answer: The practice of marrying within a small community, causing elevated DNA sharing among members
Endogamy refers to communities where people consistently marry within the same group, leading to higher-than-expected DNA sharing that can make relationship predictions less precise.
Question 5: What does the acronym 'IBD' stand for in genetic genealogy?
- Inherited Blood Disorder
- Identical By Descent (Correct answer)
- Internal Biological Data
- Inferred Biological Distance
Correct answer: Identical By Descent
IBD stands for Identical By Descent, meaning the shared DNA segment was inherited from a common ancestor rather than appearing identical by chance.
Question 6: Which major DNA testing company uses the 'Timber' algorithm to filter out population-level false segment matches?
- 23andMe
- AncestryDNA (Correct answer)
- FamilyTreeDNA
- MyHeritage
Correct answer: AncestryDNA
AncestryDNA uses the Timber algorithm to down-weight or remove DNA segments that are identical by descent at the population level rather than through a recent common ancestor.
Question 7: Within how many generations is autosomal DNA testing typically most useful for identifying genealogical relationships?
- 2–3 generations
- 5–6 generations (Correct answer)
- 8–10 generations
- 12–15 generations
Correct answer: 5–6 generations
Due to recombination, shared autosomal DNA segments become too small to reliably detect beyond approximately 5–6 generations, limiting its practical genealogical utility.
CGL Genetic Genealogy 1
Which type of DNA test traces direct patrilineal ancestry by following the Y chromosome?