Blood relations
Draw a family tree with symbols for male, female, couple and generation, then read the relation from the side of the person asked about.
Relation words to know
| Relation | Means |
|---|---|
| Father's father or mother's father | Grandfather |
| Father's brother / mother's brother | Paternal uncle / maternal uncle |
| Father's or mother's sister | Aunt |
| Brother's or sister's son / daughter | Nephew / niece |
| Uncle's or aunt's son or daughter | Cousin |
| Husband's or wife's father | Father-in-law |
| Son's wife | Daughter-in-law |
| Sister's husband; wife's or husband's brother | Brother-in-law |
| 'The only son of my father' (said by a man) | The speaker himself |
How to solve: the family-tree method
- 1Write each person once. Mark + for male and − for female only when the question tells you; a clearly male or female name, such as Arun or Meena, counts.
- 2Join a married couple with =, a parent to a child with a vertical line, and brothers and sisters with a horizontal line.
- 3Keep one generation on one level: grandparents at the top, then parents, then children.
- 4Start from the end of the sentence ('my mother's only daughter' → start at 'my mother') and work inward.
- 5Read the answer from the person asked about: 'How is A related to B?' means describe A as seen from B.
- 6If the tree does not show a person's sex, answer 'child', 'sibling' or 'cannot be determined'.
Worked example 1: pointing type
Pointing to a boy, Kavya says, 'His mother is the only daughter of my mother.' How is the boy related to Kavya?
- Step 1: start from the end: 'my mother' is Kavya's mother.
- Step 2: 'the only daughter of my mother': Kavya is herself a daughter of her mother, so the only daughter must be Kavya.
- Step 3: 'his mother is' that person, so Kavya is the boy's mother.
- Check with the tree: Kavya's mother → Kavya (−) → boy (+). The boy is one generation below Kavya and male: her son.
Son.
Worked example 2: coded relations
If A + B means A is the brother of B, A − B means A is the sister of B, and A × B means A is the father of B, how is P related to S in P × Q + R − S?
- Step 1: P × Q: P is Q's father.
- Step 2: Q + R: Q is R's brother, so Q is male and Q and R are siblings.
- Step 3: R − S: R is S's sister, so R is female and R and S are siblings.
- Step 4: Q, R and S are brothers and sisters, so P, the father of Q, is the father of all three.
- Check: every link agrees with the tree. S's own sex is never given, so the reverse relation is only 'S is P's child'.
P is the father of S.
Worked example 3: a chain with extra information
A is B's sister. C is B's mother. D is C's father. E is D's mother. How is A related to D?
- Step 1: A is B's sister, so A is female and A and B are siblings.
- Step 2: C is B's mother, so C is A's mother too.
- Step 3: D is C's father, so D is A's maternal grandfather.
- Step 4: A is female and two generations below D: A is D's granddaughter.
- Check: E (D's mother) is not needed. Questions often add extra people; use only the links you need.
Granddaughter.
Bank, SSC, railway and state PSC papers ask 'pointing to a photograph' puzzles, coded relations (A + B, A × B) and family-tree sets of 3-5 questions; placement tests add 'cannot be determined' traps where a person's sex is not given.
2 marks: “If A is the brother of B and B is the sister of C, how is A related to C?” Brother. A, B and C are siblings, and A is male.
5 marks: “Explain the family-tree method of solving blood-relation problems with an example.” Give the symbols, the one-generation-per-level rule, starting from the end of the sentence and reading from the asked person's side; solve the Kavya example with a tree.
10 marks: “Explain how blood-relation problems are solved, with the relation words, the family-tree symbols and two worked examples.” Relation words (uncle, nephew, cousin, in-laws); tree symbols; steps; a pointing example and a coded example, each with a tree.
Start from the end of the sentence, draw one generation per level, mark + and −, and answer from the asked person's side. No sex given → 'cannot be determined'.