Blood Relations — Family Puzzles

A family puzzle gives you a series of statements about how people are related — "A is the father of B," "C is the sister of B," "D is the mother of A" — and then asks about the relationship between two people. The key skill is drawing a small family tree rather than trying to hold all the links in your head. Mistakes happen when students try to reason purely in words.

1. Read all clues once to get an overview.
2. Start with the clearest clue (usually a parent-child link) and place two people on paper. Use M/F labels.
3. Add each new person by connecting them to someone already on the tree.
4. When a clue gives gender ("his wife," "her brother"), note the gender next to the name.
5. After placing everyone, trace the path between the two people in the question and name the relationship.

Example 1: P is the father of Q. R is the mother of Q. S is the brother of P. How is S related to Q?

• Tree: P (father) + R (mother) → Q (child). S is P's brother.
• S is the brother of Q's father → S is Q's uncle.
• Answer: S is Q's uncle.

Example 2: A is the mother of B. C is the husband of A. D is the son of C. B and D are siblings. E is the daughter of B. How is E related to C?

• Tree: C + A → B and D. E is B's daughter.
• C is B's father, B is E's parent → C is E's grandfather.
• Answer: C is E's grandfather.

• Assuming gender when it is not stated: "P is the child of Q" does not say whether P is a boy or girl.
• Missing that "brother of my father" = uncle, not just "father's sibling."
• Confusing maternal and paternal relations when the question asks specifically (maternal uncle vs. uncle).

1. X is the son of Y. Z is the wife of Y. How is Z related to X?
2. M is the father of N. O is the sister of M. How is O related to N?