Blood Relations

Blood Relations

🟢 Lite

Key Pattern/Rule

Draw a family tree as you read — represent each person as a node, note the relationship type, and track gender clues from the language used.

Memory Trick

“Painted Ladies Must Fortify Their Hut” = Parents, Aunts/Uncles, Siblings, Grandparents, In-laws, Spouses, Children, Cousins. Or simply build the tree as you go — male/female tags on every person.

1-Sentence Summary

Blood relation problems give you a chain of relationships and ask you to deduce a specific connection, requiring you to decode family terminology and track multiple relationships simultaneously.

Quick Example

Q: A is B’s mother. B is C’s brother. C is D’s son. How is A related to D? A: A is D’s mother-in-law — B and C are siblings; if B is C’s brother and C is D’s son, then D is B’s parent. Since A is B’s mother, A is D’s mother-in-law.

🟡 Standard

Concept

Blood relation questions test your ability to decode complex family descriptions and map them onto a family structure. The challenge isn’t just knowing who is related to whom — it’s understanding how relationship terms nest, combine, and chain together.

The key skill is translation: converting English descriptions into a family diagram. Phrases like “A is B’s only sibling’s mother” or “C is the daughter of D, who is the only son of E” require careful parsing. Each relationship term has a precise meaning, and combining them requires step-by-step logic.

The underlying principle is that every person in a family tree has a specific position. Your job is to find where each person sits relative to others, then answer questions like “how is X related to Y?” or “who is X’s uncle?”

Types & Approach

Type 1: Direct Relationship Description The simplest type. A single statement describes one relationship.

• “A is B’s brother” → A and B share the same parents, A is male.
• Approach: Draw A and B with a sibling line, mark A’s gender.

Type 2: Chained Relationships Multiple relationships linked together. You must solve them step by step.

• “A is B’s sister. B is C’s father.”
• Approach: Start from the known point (B is C’s father), then add A (B’s sister = C’s aunt).

Type 3: Coded Descriptions Language describes relationships indirectly: “A is the only child of B’s mother” or “C is the daughter of D’s only son.”

• Approach: Break into parts. “Only child” means exactly one child. “Only son” means the son is the sole male offspring.

Type 4: Generations and Gender-Based Descriptions Terms like “maternal grandfather,” “paternal grandmother,” “elder sister,” “younger brother.”

• Approach: First identify the generation (how many steps up/down), then gender, then which side (maternal/paternal).

Step-by-Step Example

Q: A is B’s sister. B is C’s mother. D is C’s brother. How is D related to A?

Approach: Step 1 → Draw B at center. B is female (A is B’s sister — same parents, same gender). Step 2 → C is B’s child. Draw C below B. Step 3 → D is C’s brother — so D is also B’s child, male. Step 4 → A is B’s sister — so A is also B’s child, female. Step 5 → A and D are siblings (share same parents — B).

Answer: D is A’s brother. (Or A is D’s sister.)

Common Mistakes

• Confusing “sister” with “brother” when gender isn’t explicitly stated → Fix: Pay attention to pronouns. “He,” “she,” “him,” “her” tell you gender.**
• Misinterpreting “only child” → Fix: “Only child” means the sole child of their parents — no siblings.**
• Treating maternal and paternal relations as interchangeable → Fix: Maternal = mother’s side, paternal = father’s side. They matter when the question specifically asks.**
• Getting confused by relationship chains that loop back → Fix: Take it one step at a time. Don’t try to solve the whole chain mentally — draw it.**

🔴 Extended

Full Concept Explanation

Blood relation problems appear in almost every GATE exam, and they’re a reliable source of marks if you approach them systematically. The underlying concept is deceptively simple: families are graphs where each person is a node and relationships are edges. But the complexity comes from the way English describes family relationships — using relative terms, nested clauses, and implicit information that you need to decode.

The fundamental principle is that every relationship in a family has three components: generation level (how many steps up or down from you), gender (male or female), and lineage (maternal or paternal side). A “maternal grandfather” is your mother’s father — one generation up, male, on your mother’s side. These three dimensions let you pin down any relationship precisely.

Relationship Terminology Deep Dive:

Siblings: Brothers and sisters share the same parents. “A is B’s sibling” means they share at least one parent. “Only sibling” means no brothers or sisters exist.

Parents: Mother and father are immediate parents. “Maternal” always refers to the mother’s side; “paternal” to the father’s side.

Grandparents: Two generations up. Your maternal grandfather is your mother’s father. Your paternal grandmother is your father’s mother.

Cousins: Children of siblings. First cousins share grandparents. Second cousins share great-grandparents.

Aunts and Uncles: Your parents’ siblings are your aunts and uncles (paternal or maternal depending on which parent). Their children are your first cousins.

In-laws: Relationships created by marriage, not blood. Your mother-in-law is your spouse’s mother. Your brother-in-law could be your spouse’s brother OR your sibling’s spouse.

The Point-to-Point Notation System: Many competitive exam toppers use a notation system that makes solving blood relations much faster:

Write relationships as a path:

• “A’s mother” → A ← Mother
• “B’s sister” → B ← Sister
• “C’s brother” → C ← Brother

When two paths meet, you find the relationship:

• A ← Mother → B (A and B are siblings)
• X ← Father → Y ← Mother → Z (X and Y are siblings; Y and Z are siblings, so X, Y, Z are all siblings)

Nesting and Chaining: Complex descriptions chain relationships. “A is B’s only sibling’s mother” can be broken down:

1. “B’s only sibling” = the one and only brother or sister of B
2. That person’s mother = A

So A is the mother of B’s only sibling — meaning A is B’s parent. And since B has an “only sibling,” there’s exactly one sibling, meaning A has exactly two children: B and B’s sibling. But the exact sibling count may not matter — what matters is A is definitely a parent of B.

Gender Clues in Language: English embeds gender information throughout relationship descriptions:

• “He,” “him,” “boy,” “man,” “brother,” “son,” “father,” “uncle,” “nephew” → Male
• “She,” “her,” “girl,” “woman,” “sister,” “daughter,” “mother,” “aunt,” “niece” → Female
• “Person,” “child,” “parent,” “sibling,” “cousin” → Gender unspecified

Words like “elder,” “younger,” “married,” “widow,” “widower” give additional context.

GATE-Level Practice

Q1: Pointing to a man, a woman said, “His mother is the only daughter of my mother.” How is the woman related to the man? Answer: The woman is the man’s mother. — The man’s mother is the only daughter of the woman’s mother → the only daughter of the woman’s mother is the woman herself. So the man’s mother = the woman. Therefore the woman is the man’s mother.

Q2: A is B’s daughter. B is C’s sister. C is D’s mother. D is E’s brother. E is F’s daughter. How is A related to F? Answer: A is F’s cousin (first cousin). — C is D’s mother, D is E’s brother → E and D are siblings sharing C as their mother. E is F’s daughter → F is E’s parent, so F is also D’s parent (since D and E are siblings). B is C’s sister, and C is D’s mother → B is D’s aunt (D’s mother’s sister). A is B’s daughter → A is the niece of D. Since D is F’s child, A and F are first cousins.

Q3: If P is Q’s mother and Q is R’s sister, and R is S’s son, how is Q related to S? Answer: Q is S’s daughter. — Q is R’s sister means Q and R share at least one parent. R is S’s son → S is R’s parent. If S is R’s parent and Q is R’s sister, then S is also Q’s parent. So Q is S’s daughter (or son, but Q is R’s sister and R is S’s son, so Q is also S’s child).

Multiple Approaches

Standard Method (Draw the Tree):

1. Identify a starting point — usually someone with clear relationships.
2. Draw them as a node.
3. Work outward, adding each new person.
4. Label gender on each node.
5. When relationships are established, find the answer.

Notation Method (Faster for Chain Questions):

1. Write each relationship as a path.
2. Chain the paths together.
3. Identify the final relationship by the generation distance and gender.

Coded Language Method (For Complex Descriptions):

1. Translate each phrase literally: “only child” = exactly one child, “only son” = exactly one male child, “elder sister” = female sibling born earlier.
2. Break complex descriptions into sequential steps.
3. Solve step by step.

Tricky Cases / Edge Cases

• “Only” variations: “Only son” means the sole male child. But “only child” means the sole child regardless of gender. Be careful — “A is my only sibling’s mother” means A is the mother of my only sibling, which means A is my parent.
• Same gender implications: If two people are described as “sisters,” they share gender and are siblings. If they’re “brothers,” they share gender and are siblings.
• Spouse chains: “A is B’s wife. B is C’s sister.” → C is A’s sister-in-law. The chain through B (spouse relationship) converts to in-law when followed through blood.
• Generation skipping: “A is B’s grandmother’s only child” → A is B’s mother (since B’s grandmother’s only child must be B’s parent).
• Ambiguous “son of” vs “daughter of”: These are gender-specific. If the problem says “son of,” the person is male. If it says “daughter of,” the person is female.
• Reciprocal relationships: If A is B’s uncle, then B is A’s nephew. Always check the question asks from the right perspective.

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