Blood Relations — Study Notes

Overview

Blood Relations is a core reasoning topic in UP Police Constable that tests your ability to decode family relationships from verbal statements. Questions present family connections through coded language ("A is B's father's only son") and ask you to identify the relationship between two people. This topic appears consistently in every exam cycle with 2–4 questions carrying straightforward marks — questions you cannot afford to miss.

Mastering blood relations requires two skills: understanding relationship terminology (both forward and backward) and systematic decoding of complex statements. Most students lose marks not because of logical errors but because they misinterpret "only son" versus "only child" or fail to consider gender. The key is translating each statement into a family tree diagram before attempting the answer. With practice, you can solve these questions in under 60 seconds each, making blood relations one of the highest-return topics for exam preparation.

Questions range from direct single-statement problems to multi-layered puzzles involving 3–4 family members. Recent patterns show increasing use of negative statements ("not the brother") and gender-neutral terms that require careful inference. Always verify your answer by checking the reverse relationship path.

Key Concepts

• **Direct relationships** — Parent, child, sibling, spouse — form the foundation. Mother/father, son/daughter, brother/sister, husband/wife must be crystal clear including gender implications.

• **Second-generation relationships** — Grandparents, grandchildren, aunts, uncles, nieces, nephews. Remember: your father's/mother's siblings become your uncle/aunt; your siblings' children become your niece/nephew.

• **In-law relationships** — Marriage creates new connections. Your spouse's parents are your in-laws; your children's spouses are your son-in-law/daughter-in-law; your spouse's siblings are your brother-in-law/sister-in-law.

• **Only child/only son logic** — "Only son" means no brothers but sisters may exist. "Only child" means no siblings at all. This distinction is the most common trap in blood relation questions.

• **Gender determination** — Words like brother, son, father, uncle automatically tell gender. Words like child, sibling, parent require you to infer gender from context or the question itself.

• **Reverse relationship principle** — If A is B's father, then B is A's son or daughter. Always verify by checking the relationship in both directions to catch logical errors.

• **Generational counting** — Count generations to avoid confusion. Parent → child is one generation down. Grandparent → parent → child is two generations. Cousin relationships stay within the same generation.

• **Self-reference statements** — "My father's only son" almost always means "I" (unless you have brothers). Decode these by replacing "my" with the speaker's name and drawing the tree.

Formulas / Key Facts

1. **Mother/Father + Son/Daughter = Parent-Child** — First-generation direct relationship.

2. **Grandparent = Parent's parent** — Father's father = paternal grandfather; mother's mother = maternal grandmother.

3. **Uncle/Aunt = Parent's sibling** — Father's brother = uncle; mother's sister = aunt.

4. **Cousin = Uncle's or Aunt's child** — Your parent's sibling's children are your cousins.

5. **Nephew/Niece = Sibling's child** — Brother's son = nephew; sister's daughter = niece.

6. **Brother-in-law = Sister's husband OR Spouse's brother** — Two distinct paths create this relationship.

7. **Sister-in-law = Brother's wife OR Spouse's sister** — Similar dual-path relationship.

8. **Son-in-law/Daughter-in-law = Child's spouse** — Marriage of your children creates in-law relationships.

9. **Only son/Only daughter** — No siblings of that gender exist, but opposite gender may exist.

10. **Only child** — Absolutely no siblings. This person is both "only son" and "only daughter" effectively.

Worked Examples

**Example 1:** Pointing to a photograph, Ramesh said, "He is the son of my grandfather's only son." How is the person in the photo related to Ramesh?

**Solution:**

• Step 1: "My grandfather's only son" = Ramesh's father (since grandfather has only one son)
• Step 2: "Son of my father" = Ramesh's brother (could also be Ramesh himself)
• Step 3: The question asks relationship to Ramesh
• **Answer:** Brother (or Ramesh himself, but typically "brother" is the expected answer when pointing to a photo)

**Example 2:** Introducing Sonia, Aman says, "She is the wife of only nephew of only brother of my mother." How is Sonia related to Aman?

**Solution:**

• Step 1: "Only brother of my mother" = Aman's maternal uncle
• Step 2: "Only nephew of my maternal uncle" = Aman's maternal uncle has only one nephew, which must be Aman himself (since nephew = sister's son, and Aman's mother is the sister)
• Step 3: "Wife of Aman" = Aman's wife
• **Answer:** Wife

**Example 3:** 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?

**Solution:**

• Draw the family tree:
• E (great-grandmother)
• D (grandfather) — child of E
• C (mother) — child of D
• B and A (siblings) — children of C
• A is C's daughter, and C is D's daughter
• Therefore A is D's granddaughter
• **Answer:** Granddaughter

Common Mistakes

**Mistake 1:** Confusing "only son" with "only child" → **Fix:** "Only son" means no brothers but sisters may exist. Always check if the statement excludes all siblings or just same-gender siblings.

**Mistake 2:** Ignoring gender clues in statements → **Fix:** Words like "he," "his," "brother," "son" immediately tell you the person is male. Build this into your diagram with M/F labels to avoid gender confusion later.

**Mistake 3:** Not drawing family trees for complex statements → **Fix:** Never attempt 3+ person relationships mentally. Invest 15 seconds drawing a simple tree with circles (female) and squares (male). Visual representation prevents logical errors.

**Mistake 4:** Assuming marriage when only blood relation exists → **Fix:** "Brother's wife" is sister-in-law but "brother" itself is blood relation. Keep blood and marital relations separate unless marriage is explicitly stated in the problem.

**Mistake 5:** Forgetting to check reverse relationships → **Fix:** If you conclude "X is Y's nephew," verify by checking "Y must be X's uncle or aunt." This double-check catches most logical errors before marking the answer.

Quick Reference

• **My father's son = My brother** (or myself if only child or only son)
• **My mother's only child = Myself** (no siblings exist)
• **My grandfather's child = My parent or uncle/aunt** (depending on which one)
• **Spouse's sibling = Brother-in-law / Sister-in-law** (in-law relation through marriage)
• **Sibling's child = Nephew / Niece** (generational shift downward)
• **Always draw trees for 3+ person puzzles** — 15 seconds invested saves 45 seconds of confusion