Blood Relation – Reasoning Concepts, Tricks & Examples
Blood Relation problems test a candidate’s ability to analyze and interpret family relationships, often involving logical deductions about family trees and lineage.
1. Generations in Blood Relations
Family members can be classified into generations relative to a reference person. Parents belong to one generation above, while children belong to one generation below.
| Generation | Family Members |
|---|---|
| +3 | Great-grandparents |
| +2 | Grandparents |
| +1 | Parents, uncles, aunts |
| 0 | Self, siblings, cousins, spouse |
| -1 | Children, nephews, nieces |
| -2 | Grandchildren |
| -3 | Great-grandchildren |
Example 1: A is the father of B. B is the mother of C. C is the father of D. How is A related to D?
Solution: A → B → C → D represents three parent-child links.
Answer: Great-grandfather.
Example 2: P is the sister of Q. Q is the father of R. R is the mother of S. How is P related to S?
Solution: P is R’s paternal aunt and belongs to the generation of S’s grandparents.
Answer: Paternal grandaunt (great-aunt).
2. Family Tree Representation
Family trees represent members across generations using connecting lines.
| Symbol | Meaning |
|---|---|
| □ | Male |
| ○ | Female |
| Horizontal line between spouses | Marriage |
| Vertical line | Parent-child relationship |
| Branching from common parents | Siblings |
Example Family Tree
A and B are married. They have two children, C and D. C is married to E, and they have two children, F and G. A, C and F are male; B, D, E and G are female.
| Question | Answer |
|---|---|
| How is A related to G? | Paternal grandfather |
| How is D related to F? | Paternal aunt |
| How is E related to B? | Daughter-in-law |
| How is G related to D? | Niece |
| How many generations are present? | Three |
3. Paternal and Maternal Relationships
Relationships through the father’s side are paternal, while relationships through the mother’s side are maternal.
Example 1: A is the brother of B. B is the mother of C. How is A related to C?
Solution: A is the brother of C’s mother.
Answer: Maternal uncle.
Example 2: P is the sister of Q. Q is the father of R. How is P related to R?
Solution: P is the sister of R’s father.
Answer: Paternal aunt.
Example 3: M is the daughter of N. N is the brother of O. O is the mother of P. How is M related to P?
Solution: N and O are siblings, so their children M and P are cousins.
Answer: Cousin.
4. Relations Through Marriage
Marriage introduces relationships such as father-in-law, mother-in-law, brother-in-law, sister-in-law, daughter-in-law and son-in-law.
Example 1: A is the brother of B. B is the wife of C. How is A related to C?
Answer: Brother-in-law.
Example 2: P is the mother of Q. Q is married to R. R is male. How is P related to R?
Answer: Mother-in-law.
Example 3: A is the father of B. B is the husband of C. D is the daughter of B and C. How is C related to A?
Answer: Daughter-in-law.
Example 4: R is the sister of S. S is married to T. T is the brother of U. How is R related to T?
Answer: Sister-in-law.
5. Only Son, Only Daughter and Only Child
These expressions have different implications in blood relation questions.
| Expression | Meaning |
|---|---|
| Only son | Exactly one male child; daughters may exist |
| Only daughter | Exactly one female child; sons may exist |
| Only child | No siblings |
| Only brother | Exactly one male sibling; sisters may exist |
| Only sister | Exactly one female sibling; brothers may exist |
Example 1: A is the only son of B. C is the daughter of B. How is C related to A?
Answer: Sister.
Example 2: Pointing towards a girl, Rahul says, “She is the daughter of the only son of my paternal grandmother.” How is the girl related to Rahul?
Solution: The only son of Rahul’s paternal grandmother is Rahul’s father. The girl is his father’s daughter.
Answer: Sister.
Example 3: A is the only child of B. C is the son of A. How is B related to C?
Answer: Grandparent (gender not specified).
6. Pointing-Based Blood Relations
These questions describe a relationship through a person or photograph.
Example 1
Question: Pointing to a man, a woman says, “He is the only son of my mother’s father.” How is the man related to the woman?
Solution: Mother’s father → Maternal grandfather. His only son → Mother’s brother.
Answer: Maternal uncle.
Example 2
Question: Pointing to a boy, Priya says, “His mother is the only daughter of my mother.” How is the boy related to Priya?
Solution: The only daughter of Priya’s mother is Priya herself.
Answer: Son.
Example 3
Question: Pointing to a photograph, Aman says, “This woman’s son is my son’s maternal uncle.” How is the woman related to Aman’s wife?
Solution: Aman’s son’s maternal uncle is his wife’s brother. The woman is the mother of that brother.
Answer: Mother.
Example 4
Question: Pointing to a girl, Rohan says, “She is the daughter of my mother’s only brother.” How is the girl related to Rohan?
Solution: Mother’s brother → Maternal uncle. His daughter → Cousin.
Answer: Cousin.
Example 5
Question: Pointing to a man, Seema says, “His wife’s mother is my mother’s only daughter.” How is the man related to Seema?
Solution: Seema is her mother’s only daughter. Therefore, the man’s wife’s mother is Seema, making the man’s wife Seema’s daughter.
Answer: Son-in-law.
7. Coded Blood Relations
In coded blood relations, symbols represent family relationships according to definitions provided in the question.
Example 1: Basic Symbols
Suppose:
- A + B means A is the father of B.
- A – B means A is the mother of B.
- A × B means A is the brother of B.
- A ÷ B means A is the sister of B.
Question: How is P related to R in P + Q – R?
Solution: P is Q’s father, and Q is R’s mother.
Answer: Maternal grandfather.
Question: How is A related to D in A × B – C + D?
Solution: A is B’s brother. B is C’s mother. C is D’s father. Thus A is the brother of D’s paternal grandmother.
Answer: Paternal granduncle.
Example 2: Coded Relations with Marriage
Suppose:
- A @ B means A is the husband of B.
- A # B means A is the daughter of B.
- A $ B means A is the brother of B.
- A % B means A is the mother of B.
Question: How is P related to R in P $ Q # R?
Solution: P is Q’s brother, and Q is R’s daughter. Therefore, P is also R’s child and is male.
Answer: Son.
Question: How is P related to S in P @ Q % R $ S?
Solution: P is Q’s husband. Q is R’s mother. R is S’s brother. Therefore, Q is also S’s mother, and P is her husband.
Answer: Father.
8. Gender and Uncertain Relationships
Some statements establish a family relationship without specifying the gender of a person. In such cases, the precise gender-specific relation cannot be determined.
Example 1: A is the sibling of B. B is the mother of C. How is A related to C?
Answer: Maternal uncle or maternal aunt.
Example 2: A is the father of B. C is the daughter of A. How is B related to C?
Answer: Brother or sister.
Example 3: P is the brother of Q. Q is the child of R. How is R related to P?
Answer: Father or mother.
Example 4: A is married to B. B is the sister of C. C is the father of D. How is A related to D?
Answer: Uncle or aunt by marriage, depending on A’s gender.
9. Family-Based Puzzles with Multiple Generations
These questions combine relationships, gender, marriage, and the number of generations in a family.
Example 1: Three-Generation Family
A family has six members: P, Q, R, S, T and U.
- P and Q are married.
- R is the son of P.
- S is the wife of R.
- T is the daughter of R.
- U is the brother of T.
- P is male.
| Question | Answer |
|---|---|
| How is Q related to U? | Paternal grandmother |
| How is S related to P? | Daughter-in-law |
| How is T related to Q? | Granddaughter |
| How many generations are present? | Three |
| How many married couples are present? | Two |
Example 2: Eight-Member Family
Eight members A, B, C, D, E, F, G and H belong to three generations.
- A is married to B.
- C is the son of A and B.
- D is the daughter of A and B.
- C is married to E.
- F is the son of C and E.
- G is the daughter of C and E.
- D is married to H.
- A and H are male.
| Question | Answer |
|---|---|
| How is A related to G? | Paternal grandfather |
| How is D related to F? | Paternal aunt |
| How is E related to B? | Daughter-in-law |
| How is H related to C? | Brother-in-law |
| How is G related to D? | Niece |
| How many males are present? | Four |
| How many females are present? | Four |
| How many married couples are present? | Three |
10. Advanced Mixed Blood Relation Examples
Example 1
Question: A is the mother of B. B is the sister of C. C is married to D. D is the father of E. How is A related to E?
Solution: A is C’s mother. C and D are E’s parents.
Answer: Maternal grandmother.
Example 2
Question: P is the son of Q. Q is the sister of R. R is the father of S. S is the brother of T. How is P related to T?
Solution: Q and R are siblings. P is Q’s son, and T is R’s child.
Answer: Cousin.
Example 3
Question: A is the wife of B. C is the daughter of A. D is the son of C. E is the brother of B. How is E related to D?
Solution: B is D’s maternal grandfather. E is the brother of D’s maternal grandfather.
Answer: Maternal granduncle.
Example 4
Question: A is the brother of B. B is the mother of C. C is the wife of D. D is the father of E. How is A related to E?
Solution: A is the maternal uncle of C. C is E’s mother, so A is the brother of E’s maternal grandmother.
Answer: Maternal granduncle.
Example 5
Question: M is the father of N. N is the sister of O. O is the father of P. P is the mother of Q. How is M related to Q?
Solution: M is O’s father, O is P’s father, and P is Q’s mother.
Answer: Great-grandfather.
Example 6
Question: A is the only daughter of B. C is the brother of A. D is the son of C. E is the daughter of D. How is A related to E?
Solution: A is D’s paternal aunt. E is D’s daughter.
Answer: Paternal grandaunt.
Example 7
Question: A is the father of B. B is the husband of C. D is the sister of C. E is the son of D. How is B related to E?
Solution: C is E’s maternal aunt, and B is C’s husband.
Answer: Uncle by marriage.
Example 8
Question: P is the mother of Q. R is the husband of P. S is the daughter of Q. T is the brother of S. How is R related to T?
Solution: R is Q’s father. T is Q’s son.
Answer: Maternal grandfather.
11. Common Relationship Chains
| Relationship Chain | Result |
|---|---|
| Father’s brother | Paternal uncle |
| Mother’s brother | Maternal uncle |
| Father’s sister | Paternal aunt |
| Mother’s sister | Maternal aunt |
| Mother’s brother’s daughter | Maternal cousin |
| Father’s sister’s son | Paternal cousin |
| Brother’s daughter | Niece |
| Sister’s son | Nephew |
| Mother’s mother’s mother | Maternal great-grandmother |
| Father’s father’s father | Paternal great-grandfather |
| Father’s father’s brother | Paternal granduncle |
| Mother’s mother’s sister | Maternal grandaunt |
| Wife’s brother | Brother-in-law |
| Husband’s sister | Sister-in-law |
| Daughter’s husband | Son-in-law |
| Son’s wife | Daughter-in-law |