Blood Relations • Topic 2 of 4

Single-Person Relations

These chain several links: 'A is the son of B, B is the sister of C — how is C related to A?'. Solve from the last person backwards, keeping a gender flag on each person.

Solve the chain backwards

Read a chain like "A is the son of B. B is the sister of C." from the last named person back to the first, drawing as you go:

  1. "A is the son of B" ⇒ B is A's parent. (B's gender comes next.)
  2. "B is the sister of C" ⇒ B is female (A's mother), and C is B's sibling.
  3. So C is the brother/sister of A's mother ⇒ C is A's maternal uncle or aunt.
B (mother) — sibling — C A C = A's maternal uncle / aunt
Build the tree from the last clue backwards; the answer reads straight off it.
Keep a gender flag. The final answer is often uncle vs aunt, grandfather vs grandmother — decided by one person's gender. If the gender is not given, the answer must stay "uncle or aunt".

✅ Solved examples

1. A is the son of B. B is the sister of C. How is C related to A?
B is A's mother; C is B's sibling → C is A's maternal uncle or aunt.
2. P is the father of Q. Q is the mother of R. How is P related to R?
Q is R's mother, P is Q's father → P is R's maternal grandfather.
3. X is the brother of Y. Y is the father of Z. How is X related to Z?
X and Y are siblings; Y is Z's father → X is Z's paternal uncle.
4. M is the wife of N. N is the son of O. How is O related to M?
N is M's husband; O is N's parent → O is M's father-in-law or mother-in-law.

✏️ Practice — try these, take hints as needed

1. A is the daughter of B. B is the son of C. How is C related to A?
B is A's father.
C is B's parent.
—
Grandparent (paternal)
2. P is the mother of Q. Q is the brother of R. How is P related to R?
Q & R siblings.
—
—
Mother
3. X is the husband of Y. Y is the sister of Z. How is Z related to X?
Y is X's wife.
Z is Y's sibling.
—
Sister-in-law / brother-in-law
4. A is the son of B. C is the mother of B. How is C related to A?
B is A's parent.
—
—
Grandmother (paternal)
5. M is the brother of N. N is the father of O. How is M related to O?
M & N siblings.
—
—
Uncle (paternal)

📝 Topic test — 8 questions

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