Question 1

Which of the following best describes the difference between genealogical ancestry and genetic ancestry?

Accepted Answer

Genealogical ancestry refers to all individuals in your pedigree, while genetic ancestry refers to the subset of those ancestors from whom you inherited segments of DNA.

Question 2

In the context of the ancestral recombination graph (ARG), what does each node represent?

Accepted Answer

An ancestor in which a recombination or coalescence event occurred.

Question 3

Why is it misleading to summarize ancestry in terms of discrete categories such as 'British' or 'Huguenot'?

Accepted Answer

Because such labels can impose contemporary political or cultural divisions that may not reflect true ancestral relationships.

Question 4

Suppose you have eight great-grandparents, and one belonged to group X. What proportion of your genealogical ancestry would you typically claim from group X?

Accepted Answer

$$\frac{1}{8}$$

Question 5

Which of the following statements about the ARG (ancestral recombination graph) is correct?

Accepted Answer

The ARG only includes ancestors who contributed genetic material to the present individual.

Question 6

Why do full siblings have identical genealogical ancestry but different genetic ancestry?

Accepted Answer

Because they inherit different combinations of chromosomal segments due to meiotic recombination.

Question 7

What is a major limitation of using genetic similarity (e.g., from PCA or ADMIXTURE) to infer ancestry?

Accepted Answer

Genetic similarity can be sensitive to the choice and labeling of reference populations, potentially leading to misinterpretation.

Question 8

If a population geneticist uses an admixture graph to summarize ancestry, what is a potential drawback of this approach?

Accepted Answer

Admixture graphs may enforce the idea of discrete populations, which can oversimplify the true complexity of ancestry.

Question 9

Which of the following best explains why some ancestors in your pedigree may not be represented in your genetic ancestry?

Accepted Answer

Because only ancestors who contributed DNA segments to your genome are included in your genetic ancestry.

Question 10

A consumer genomics company tells a customer they are '30% Scandinavian.' According to the study material, what is a key caveat to this statement?

Accepted Answer

This percentage reflects genetic similarity to present-day Scandinavian reference populations, which may not correspond to actual ancestral populations.

Question 11

Which method is most directly related to reconstructing the ancestral recombination graph (ARG)?

Accepted Answer

Admixture graph

Question 12

Why is it difficult to reconstruct an individual's complete genetic ancestry from genetic data alone?

Accepted Answer

Because reconstructing the ARG from genetic variation is a highly challenging problem, even with recent advances.

Question 13

If you want to estimate the number of genealogical ancestors you have $$N$$ generations ago, which formula would you use?

Accepted Answer

$$2^N$$

Question 14

Which of the following is a potential source of bias in ancestry inference for individuals from underrepresented populations?

Accepted Answer

Attribution of ancestry to better-represented groups due to limited reference data.

Question 15

Which of the following best describes the relationship between genetic ancestry and genealogical ancestry?

Accepted Answer

Genetic ancestry in category X implies genealogical ancestry in X, but not vice versa.

Question 16

A researcher uses PCA to analyze genetic data from several populations. What is a limitation of interpreting PCA results as direct evidence of ancestry?

Accepted Answer

PCA provides only indirect summaries of genetic similarity, not explicit ancestral relationships.

Question 17

Why might the statement 'your ancestors lived in Ireland' be misleading when based solely on genetic similarity?

Accepted Answer

Because genetic similarity may reflect shared ancestry from much earlier times and different regions due to migration and population replacement.

Question 18

Which of the following is a reason why summaries of ancestry always involve a loss of information?

Accepted Answer

Because focusing on a category X ignores details of all ancestors not in X and any 'non-X' aspects of ancestors in X.

Genetic Ancestry: Concepts, Methods, and Interpretation

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