Blood Relations — SSC CHSL Study Notes

Overview

Blood Relations is a core Reasoning topic in SSC CHSL Tier 1, regularly contributing 1–3 questions per paper. These problems test your ability to decode family relationships from verbal descriptions and either identify a specific relation or trace a connection between two persons.

Exam questions take three main forms: **direct relationship identification** (A is B's father; what is B to A?), **coded/pointing problems** (pointing to a photograph, a person says "Her mother is the only daughter of my mother"), and **family-tree puzzles** (multiple statements building a multi-generational tree). Mastery requires clarity on gender-specific terms (niece vs. nephew, maternal vs. paternal), generational direction (ascendant vs. descendant), and systematic diagram-drawing. Most errors come from misreading "only daughter" logic or confusing in-law versus blood relations. With practice, this is a high-accuracy topic where you can score full marks in under a minute per question.

Key Concepts

• **Generation levels**: Parents/uncles/aunts are one generation up (+1), siblings/cousins are same generation (0), children/nieces/nephews are one down (–1), and grandparents/grandchildren are ±2 respectively. Track vertical movement to avoid mixing generations.

• **Gender markers**: Always assign M (male) or F (female) when drawing trees. Terms like son, father, brother, husband, uncle, nephew are male; daughter, mother, sister, wife, aunt, niece are female. "Sibling" or "child" can be either gender.

• **"Only" keyword traps**: "Only son" means exactly one son (no brothers, but sisters may exist unless stated "only child"). "Only daughter of my mother" means the speaker herself if female, creating a self-reference chain often tested in coded problems.

• **In-law relationships**: Spouse's relatives or sibling's spouses. Mother-in-law is your spouse's mother or your child's spouse's mother. Brother-in-law can be your sister's husband, your spouse's brother, or your spouse's sister's husband — context determines which.

• **Maternal vs. paternal**: Maternal uncle (mama) is mother's brother; paternal uncle (chacha/tau) is father's brother. Maternal aunt (mausi) is mother's sister; paternal aunt (bua) is father's sister. Grandparents follow the same split.

• **Symmetric relations**: If A is B's uncle, B is A's nephew/niece. If A is B's cousin, B is also A's cousin. Use symmetry to reverse-check your answer.

• **Diagramming discipline**: Use + for male, ○ for female, = for marriage/horizontal sibling line, and | for parent-child vertical line. Write names inside symbols. Horizontal = same generation; vertical = parent/child link. Always start from a reference person and expand outward.

• **Coded statements method**: Replace pronouns with actual names, identify the reference person (usually "my"), then trace step-by-step. Example: "His mother" → go to the speaker's father's wife if "his" refers to speaker's brother.

Key Facts

1. **Brother's wife** = sister-in-law (bhabhi). **Sister's husband** = brother-in-law (jija). 2. **Father's brother** = paternal uncle. **Father's sister** = paternal aunt. **Mother's brother** = maternal uncle. **Mother's sister** = maternal aunt. 3. **Cousin** = uncle's or aunt's child, same generation as you. 4. **Nephew** = brother's or sister's son (male, –1 generation). **Niece** = brother's or sister's daughter (female, –1 generation). 5. **Grandson/Granddaughter** = son's or daughter's child (–2 generation). 6. **Father-in-law** = spouse's father. **Mother-in-law** = spouse's mother. 7. **Son-in-law** = daughter's husband. **Daughter-in-law** = son's wife. 8. **Only child** = no siblings at all. **Only son** = no brothers, may have sisters.

Worked Examples

**Example 1 (Direct relationship)** Statement: Pointing to a man, Priya said, "His brother's father is the only son of my grandfather." *Question*: How is the man related to Priya?

**Solution**:

• "Only son of my grandfather" = my father (since Priya's father is the single son).
• "His brother's father" = the man's father = my father.
• So the man's father = Priya's father → the man is Priya's brother.

**Answer**: Brother.

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**Example 2 (Family-tree puzzle)** Statements: 1. A is the father of B and C. 2. D is the wife of A. 3. E is the brother of B. 4. F is the daughter of D.

*Question*: How is F related to E?

**Solution**: Draw the tree:

• A (M) married to D (F). Children of A and D: B, C, E, F.
• Statement 3 says E is brother of B → E is male, same generation as B.
• Statement 4 says F is daughter of D → F is female child of D (and A).
• All four (B, C, E, F) are siblings.
• E is male, F is female, same generation → F is E's sister.

**Answer**: Sister.

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**Example 3 (Coded "only daughter" trap)** Statement: Looking at a portrait, a woman says, "Her mother is the wife of my father but she is not my sister." *Question*: Who is in the portrait?

**Solution**:

• "Wife of my father" = my mother.
• "Her mother" = portrait person's mother = my mother.
• So portrait person is my mother's child.
• She is not my sister → the only remaining option is the speaker herself (if female) or the speaker's daughter.
• Since "she is not my sister" rules out sibling, the portrait must be of the speaker's **daughter**.

**Answer**: Daughter.

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**Example 4 (Generation counting)** Statement: Rina is the granddaughter of Mohan, who is the father of Pradeep. Pradeep is the father of Arjun. *Question*: How is Rina related to Arjun?

**Solution**: Tree:

• Mohan → Pradeep → Arjun (three generations down: grandfather–father–son).
• Rina is granddaughter of Mohan → Rina is Pradeep's daughter.
• Pradeep's children: Rina (F), Arjun (M).
• Rina and Arjun are siblings (brother-sister).

**Answer**: Sister (Rina is Arjun's sister).

Common Mistakes

1. **"Only daughter" confusion** → Students assume "only daughter of my mother" means a separate person. *Fix*: If the speaker is female and her mother has only one daughter, the speaker herself is that daughter. Always check if self-reference applies.

2. **Mixing in-law with blood** → Calling spouse's brother "brother" instead of "brother-in-law." *Fix*: Blood relation = direct lineage or sibling. In-law = through marriage. Keep them distinct.

3. **Ignoring gender in answers** → Writing "sibling" when the question demands "brother" or "sister." *Fix*: Read the question carefully; if gender is specified or the answer options split by gender, commit to male or female.

4. **Backward generation movement** → Confusing "son of my father" (which could be me or my brother) with "father of my son" (which is always me if male). *Fix*: Trace direction: "of my X" goes from me → X, then the next relation goes from X outward.

5. **Overcounting "only"** → Assuming "only son" means "only child." *Fix*: "Only son" = no other sons (sisters can exist). "Only child" = no siblings at all. The word "child" must appear for the stronger condition.

Quick Reference

• **Uncle's/Aunt's child** = Cousin (same generation).
• **Brother's/Sister's child** = Nephew (M) or Niece (F) (one generation down).
• **"Only son of my grandfather"** = my father (if he's the sole son).
• **"Her mother is my mother"** → She is my sister or I am she (if both female).
• **In-laws**: Add "-in-law" for spouse's family or child's spouse.
• **Always draw a quick tree** for multi-step or puzzle problems — visual clarity prevents 90 % of errors.