Blood relations: Reasoning Ability Notes for Bihar TET (Teacher Eligibility)

Blood Relations – Study Notes

(For Bihar TET – Reasoning Ability)

1. Simple Explanation

Blood relations are relationships that arise from the family tree – i.e., the relationship between a person and his/her relatives through birth.
They are direct (parent‑child, sibling) or indirect (cousins, in‑laws, etc.).

In reasoning tests you will usually be asked to identify:

Relation	How it is described in the problem	Example
Father / Mother	Parent	“X’s father is Y”
Brother / Sister	Sibling	“X is the brother of Y”
Son / Daughter	Child	“X is the son of Y”
Grand‑parent / Grand‑child	1 generation removed	“X is the grandson of Y”
Aunt / Uncle	Sibling of a parent	“X is the aunt of Y”
Cousin	Child of siblings	“X is the cousin of Y”
In‑law	Spouse’s relative	“X is the father‑in‑law of Y”

2. Key Points to Remember

#	Concept	Why it matters
1	Generational distance	The number of “links” between two people (e.g., parent–child = 1, grandparent–grandchild = 2).
2	Direction of relation	“X is Y’s father” ➜ X is higher in the tree; “Y is X’s son” ➜ Y is lower.
3	Symmetry	If X is Y’s brother, then Y is X’s brother.
4	Cross‑branch relations	Cousins, uncles/aunts, nephews/nieces are not in the same vertical line.
5	In‑law terms	They involve a spouse’s side (e.g., father‑in‑law, son‑in‑law).
6	Multiple relationships	One person can hold more than one relation to another (e.g., A is both nephew and brother‑in‑law of B).
7	Common abbreviations
* P = Parent, C = Child, S = Sibling, G = Grandparent/Grandchild, A = Aunt/Uncle, N = Nephew/Niece, I = In‑law.
8	Rule of thumb for “cousin”	Two people are first cousins if their parents are siblings. Second cousins share great‑grandparents, etc.
9	Spouse’s relation	Spouse’s parents = in‑laws; spouse’s siblings = brother‑in‑law / sister‑in‑law.
10	Avoid confusion	“X is Y’s brother” does not mean X is Y’s son (unless gender changed).

3. Worked Example

Problem Statement

A is the mother of B.
B is the sister of C.
C is the father of D.
E is the brother of F.
F is the daughter of D.

Question:
What is the relationship between A and E?

Step‑by‑Step Solution

Step	Statement	Relationship built
1	A → mother → B	A is B’s mother
2	B → sister → C	B is C’s sister → C is B’s brother
3	C → father → D	C is D’s father
4	D → parent of → F	D is F’s parent
5	F → sister → E	F is E’s sister
6	D → parent of → F → sister of E	D is also the sibling of E’s parent? No, D is parent of F, and F is sibling of E → D is E’s parent
7	C → father of D → parent of E	C is E’s grandfather
8	B → sister of C → B is C’s sister → B is E’s great‑aunt? No, B is sister of C (E’s grandfather) → B is E’s great‑aunt (since B is the sister of E’s grandfather).
9	A → mother of B → A is B’s mother → A is also the great‑aunt of E?	A is sister of C? No, A is mother of B, who is sister of C. Thus, A is the great‑aunt of E.

Answer:
A is the great‑aunt of E (or equivalently, E is the grand‑niece of A).

Quick Verification

C (E’s grandfather) → B (C’s sister) → A (mother of B).
So A is the sister of E’s grandfather → great‑aunt. ✔️

4. Quick Revision Summary

Topic	Key Take‑away
Generational distance	Count the number of links.
Parent/Child	Direct vertical link.
Sibling	Share same parents.
Grand‑relations	One more link up/down.
Aunt/Uncle & Nephew/Niece	Sibling of parent / child of sibling.
Cousins	Children of siblings; first cousins share grandparents.
In‑law	Spouse’s side (father‑in‑law, brother‑in‑law, etc.).
Multiple roles	One person can be both aunt and sister‑in‑law, etc.
Common abbreviations	P, C, S, G, A, N, I.
Practice tip	Draw a small family tree for each problem.

Final Checklist Before Exam

Identify the direction of each relation given.
Count generations between the two people.
Mark each relationship on a quick diagram.
Check for multiple possible relations (e.g., could be both nephew and brother‑in‑law).
Choose the most accurate based on the problem