SSC CGL Reasoning · Free notes
Blood Relations: SSC CGL Reasoning
Blood Relations has 154 questions in the SSC CGL Tier I bank, and 70 of them come from the 2025 shifts. None is HARD: 95 are EASY and 59 MODERATE, so the chapter tests care and speed rather than depth, at about 36 seconds a question. Whatever form a question takes, one small family tree solves it: a level for each generation, a mark for each gender, a line for each marriage. The marks are lost in three places: answering the relation the wrong way round, giving someone a gender no clue states, and passing over a printed 'Cannot be determined'.
The handout has every subtopic, worked example, formula and trap with answers shown. The formula sheet is the chapter’s formulas and traps alone, on one page.
Subtopic notes
Direct Relations
35 PYQsShort chains of plain statements such as 'A is the brother of B. B is the son of C', solved by placing each person on a small family tree, one statement at a time.
Spoken Relation Chains
51 PYQsOne person describes another through a chain of possessives, such as 'my mother's brother's son', and you shorten the chain one step at a time, starting from the speaker.
Family Puzzles
11 PYQsA set of clues about a whole family, often out of order, from which you build one tree and then answer a relation or count the men, women or couples.
Coded Relations
44 PYQsSymbols stand for relations ('A @ B means A is the mother of B'), and a chain like 'K # L @ M' is decoded into plain links and drawn as a family tree.
Coded Statements and Expressions
13 PYQsCoded questions turned round: either test four statements against one decoded chain, or test four chains to find the one that gives a stated relation.
Formula & revision sheet
0 formulas · 1 reference tables · 27 gotchas across all subtopics — the exam-eve cheat-sheet
Formula & revision sheet
0 formulas · 1 reference tables · 27 gotchas across all subtopics — the exam-eve cheat-sheet
Watch out for (8)
- Answering the relation the wrong way round→ Counting generations up and down a family tree
- Calling every grandmother paternal→ Counting generations up and down a family tree
- Treating a sibling's wife as a sibling→ Siblings share the same parents
- Stopping one step early→ Siblings share the same parents
- Putting a cousin on the wrong level→ Uncles, aunts, nephews, nieces and cousins
- Mixing paternal and maternal uncles→ Uncles, aunts, nephews, nieces and cousins
- Taking a gender from the word on the right→ When a gender is fixed, and when the answer cannot be determined
- Skipping a printed 'Cannot be determined'→ When a gender is fixed, and when the answer cannot be determined
Reference tables (1)
In-law relations through a husband or wife8 rows
| Relation | Who it is | Level |
|---|---|---|
| Father-in-law | the father of your husband or wife | one up |
| Mother-in-law | the mother of your husband or wife | one up |
| Son-in-law | the husband of your daughter | one down |
| Daughter-in-law | the wife of your son | one down |
| Brother-in-law | your husband's or wife's brother, or your sister's husband | same |
| Sister-in-law | your husband's or wife's sister, or your brother's wife | same |
| Wife's sister's husband | a co-brother, keyed by SSC as a brother-in-law | same His son is your nephew, as is the son of any brother-in-law. |
| Husband's or wife's sibling's child | your nephew or niece | one down |
Watch out for (6)
- Starting the chain from the far end→ Shortening a possessive chain from the speaker outward
- Answering for the wrong person→ Shortening a possessive chain from the speaker outward
- Collapsing 'only son' to a woman speaker→ When the chain points back to the speaker
- Calling the speaker's sibling 'myself' too soon→ When the chain points back to the speaker
- Taking a mother's son-in-law as your husband every time→ In-law relations through a husband or wife
- Calling a cousin's wife a sister-in-law without checking→ In-law relations through a husband or wife
Watch out for (4)
- Forcing a clue before its people are placed→ Placing clues that come out of order
- Letting a spare clue change the answer→ Placing clues that come out of order
- Counting a person twice→ Families of a given size: couples, generations and counting members
- Counting an open gender as male→ Families of a given size: couples, generations and counting members
Watch out for (5)
- Reading a code from the wrong side→ Decoding a symbol chain link by link
- Carrying a code over from another question→ Decoding a symbol chain link by link
- Leaving the answer person's gender open→ Decoding a symbol chain link by link
- Making the other parent a second mother→ Filling a gap: the other parent and a gender fixed by a later link
- Missing a reversed code→ Filling a gap: the other parent and a gender fixed by a later link
Watch out for (4)
- Treating 'possible' as 'correct'→ Checking which statement is correct or NOT correct
- Checking only the two ends of the chain→ Checking which statement is correct or NOT correct
- Decoding every option in full→ Finding the expression that gives a stated relation
- Building the path from the wrong end→ Finding the expression that gives a stated relation
PYQ weightage by concept
13 concepts · 154 PYQs — where the marks actually sit, so you know what to drill first
PYQ weightage by concept
13 concepts · 154 PYQs — where the marks actually sit, so you know what to drill first
| Concept | PYQs | Share |
|---|---|---|
| Siblings share the same parents | 12 | 8% |
| Counting generations up and down a family tree | 10 | 6% |
| Uncles, aunts, nephews, nieces and cousins | 7 | 5% |
| When a gender is fixed, and when the answer cannot be determined | 6 | 4% |
| Concept | PYQs | Share |
|---|---|---|
| When the chain points back to the speaker | 21 | 14% |
| Shortening a possessive chain from the speaker outward | 15 | 10% |
| In-law relations through a husband or wife | 15 | 10% |
| Concept | PYQs | Share |
|---|---|---|
| Placing clues that come out of order | 7 | 5% |
| Families of a given size: couples, generations and counting members | 4 | 3% |
| Concept | PYQs | Share |
|---|---|---|
| Decoding a symbol chain link by link | 27 | 18% |
| Filling a gap: the other parent and a gender fixed by a later link | 17 | 11% |
| Concept | PYQs | Share |
|---|---|---|
| Checking which statement is correct or NOT correct | 8 | 5% |
| Finding the expression that gives a stated relation | 5 | 3% |
Test yourself on Blood Relations
20 past SSC CGL questions from this chapter, timed at 12 minutes and marked the way the exam marks it. You see your score and every answer the moment you finish. Free to start.