Last reviewed 22 Sept 2026 · 6 min read
Draw, do not think
Every blood-relation question is answered faster on paper than in the head. Use one set of symbols and never vary it:
- Put each generation on its own line — grandparents on top, then parents, then children.
- Join a married couple with a horizontal line; hang children below their parents.
- Mark male (+) and female (−) beside each person, and leave it blank when the question has not said.
- Work from the end of the sentence backwards: in "the son of the sister of my father", start with "my father".
Read a long sentence in pieces, marking each piece on the tree before reading the next. "He is the only son (1) of the wife (2) of my mother's brother (3)" is three small facts, not one hard one.
The vocabulary
| Phrase | Means |
|---|---|
| Father's father / mother | Paternal grandfather / grandmother |
| Mother's father / mother | Maternal grandfather / grandmother |
| Father's brother | Uncle (paternal) |
| Father's sister | Aunt (paternal) |
| Mother's brother | Maternal uncle |
| Mother's sister | Maternal aunt |
| Brother's or sister's son | Nephew |
| Brother's or sister's daughter | Niece |
| Uncle's or aunt's child | Cousin (no gender in English) |
| Husband's or wife's father | Father-in-law |
| Sister's husband | Brother-in-law |
| Brother's wife | Sister-in-law |
| Son's wife | Daughter-in-law |
| Grandson's or granddaughter's child | Great-grandchild |
Two useful simplifications: father's or mother's child is a sibling (brother or sister), and the only son of my grandfather is my father — provided the question calls him that.
The question formats
- Single sentence: "Pointing to a man, a woman said, 'His mother is the only daughter of my mother.'" — build the tree and read off the answer.
- Introducing / photograph: the speaker's own place in the tree is the anchor. Mark the speaker first, always.
- Puzzle form: several sentences about a family of six or seven, asking for a relation, the number of females, or who is married to whom.
- Coded relations: symbols carry meaning, for example = A is the father of B, = A is the wife of B. Translate the whole expression symbol by symbol, right to left.
English relation words that carry no gender are cousin, spouse and child; and a "son of my uncle" could be married to anyone. If a question never states a gender, the answer cannot depend on it — options that do are there to catch a guess.
Worked examples
Pointing to a photograph, a man said, "I have no brother or sister, but that man's father is my father's son." Who is in the photograph?
Solution. "My father's son" with no brothers is the speaker himself. So that man's father is the speaker → the photograph is of his son.
A woman said, "His mother is the only daughter of my mother." How is the woman related to the man?
Solution. The only daughter of her mother is the woman herself, so she is his mother → she is his mother.
If P is the brother of Q, and Q is the daughter of R, how is P related to R?
Solution. Q is R's daughter, and P is Q's brother, so P is R's son.
A is B's father's sister's son. How is A related to B?
Solution. B's father's sister is B's aunt; her son is B's cousin.
X is the husband of Y. Z is the only sister of X. How is Z related to Y?
Solution. Z is Y's sister-in-law.
The son of my mother's only brother is my …?
Solution. My mother's brother is my maternal uncle; his son is my cousin.
If means A is the father of B, means A is the wife of B, and means A is the brother of B, then what does mean?
Solution. Read right to left: R is the brother of S; Q is the father of R; P is the wife of Q. So P is the mother of S (and of R).
In a family, there are a husband, a wife, their two sons and the wife of the elder son. How many males are there?
Solution. Husband, two sons → 3 males (the wife and the daughter-in-law are the two females).
A is the mother of B. C is the son of A. D is the brother of E. E is the daughter of B. Who is the grandmother of E?
Solution. E is B's daughter and B is A's child, so A is E's grandmother.
P is the child of Q. R is the only sibling of P. Is R male or female?
Solution. It cannot be decided — "sibling" carries no gender. Any option naming a gender is wrong.