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Blood Relations

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high importance~2-4 Q in Tier 13 formulas⚡ 8 shortcuts4 subtopics
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How to solve blood-relation questions

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⏱ 5 min read🧩 5 question types🎯 12 practice Q
The idea in one minute

A blood-relation question gives you a few sentences about one family. Your job is to draw them as a family tree and read the answer off it. Two habits protect every mark: never guess a gender, and answer in the direction the question asks. The method below works for every question in this topic.

01

What these questions really test

They never test your knowledge of families. They test one skill: turning spoken sentences into a small drawing with zero slips. That drawing is a family tree. Build the tree, and the answer is one line.

Tip: Draw every question, even a two-line one. Chains kept in the head cause most wrong answers in this topic.

02

The symbols for a tree

Use the same marks every time, so your hand never has to think:

MarkMeaning
M / Fmale / female
=husband and wife
arrow downparent to child
one rowbrothers and sisters

Elders sit on the top rows. A child sits one row below its parents. A married couple always shares one row.

Rule: A marriage joins two people of the same row. A child sits one row below its parents.

03

Solve in three steps

  1. Mark genders. Write M or F only where a word fixes it. Father, brother, son, uncle, husband mean male. Mother, sister, daughter, aunt, wife mean female.
  2. Turn each sentence into a link. "Rita's son is Amit" becomes one arrow, Rita to Amit (M). Take one sentence at a time.
  3. Read the tree. Find the two people named in the question. Count the arrows between them. Write the relation.

Watch: Cousin, child, parent fix no gender. Leave those names blank. A blank gender is often the whole answer.

04

Answer in the asked direction

"How is A related to B?" means: name A from B's side. A is B's blank. So start at B, walk to A, and fill the blank.

The same tree answers both directions with mirror words:

If A is B's...then B is A's...
father / motherson / daughter
grandfather / grandmothergrandson / granddaughter
uncle / auntnephew / niece
cousincousin

Watch: The exam loves to reuse one tree with the question flipped. Read the last line before you mark.

05

Count generations on the tree

Every arrow is one generation. Count arrows, then pick the word:

Arrows betweenGoing upGoing down
1father / motherson / daughter
2grandfather / grandmothergrandson / granddaughter
3great-grandfathergreat-grandson

Sideways words, the ones students mix up:

  • Same parents: brother or sister.
  • Parent's brother or sister: uncle or aunt.
  • Uncle's or aunt's child: cousin (never nephew).
  • Sibling's child: nephew (boy) or niece (girl).
06

Words that mean "only one"

  • Only child: no brother and no sister at all.
  • Only son: no other boy. A sister may still exist.
  • Only daughter: no other girl. A brother may still exist.

Watch: "Only son" and "only child" build different trees. Read the exact word before you draw.

07

Question types you will see

Each type: how to recognise it, the method step by step, and one question to try.

Type 1very common3 practice Q

Which direction is the question asking

How to spot it:

'How is A related to B?' or the same question flipped: 'How is B related to A?'

Method

  1. Draw the one or two links the statement gives.

  2. Start from the person named after 'related to'. That person is your viewpoint.

  3. Walk the tree to the other person and name them from this side.

Why it works:

The same tree gives opposite words in opposite directions, so fix the viewpoint before naming anything.

Try this

Sunita is the mother of Deepak. How is Deepak related to Sunita?

Show solution

  1. Arrow: Sunita down to Deepak, marked M.

  2. The question names Sunita after 'related to', so look from her side.

  3. Deepak sits one arrow below Sunita and is male.

Answer

Son

Type 2common3 practice Q

Gender never fixed: cannot be determined

How to spot it:

The options include 'Cannot be determined', or the chain ends in a gender-free word like cousin, child, sibling.

Method

  1. Give a gender only to people named by a gendered word (father, sister, wife and so on).

  2. Check whether the asked relation needs a gender that stayed blank.

  3. If it does, choose 'Cannot be determined' or the neutral word.

Why it works:

A relation like son or daughter needs a gender. No statement gave one, so no single option is provable.

Try this

A and B are siblings. C is A's mother. How is B related to C?

Show solution

  1. B shares a parent with A, so C is B's mother too.

  2. The question now needs B's gender.

  3. No word in the question fixes B's gender.

Answer

Son or daughter: cannot be determined

Type 3very common3 practice Q

Two sentences, one small tree

How to spot it:

Two short sentences, each naming one link, such as 'R is the father of S. T is the sister of S.'

Method

  1. Draw one link per sentence: an arrow for parent and child, one row for siblings.

  2. Merge them: people under the same arrow are siblings.

  3. Read the path between the two named people.

Why it works:

Two links already fix a three-person tree, and the question is just one path on it.

Try this

R is the father of S. T is the sister of S. How is T related to R?

Show solution

  1. Draw R above S. Put T on S's row, marked F.

  2. Same row means same parents.

  3. T is one arrow below R and female.

Answer

Daughter

Type 4common3 practice Q

Counting members of a family

How to spot it:

'How many female/male members are there in the family?' after a short description.

Method

  1. Draw every person as a box, including each named husband or wife.

  2. Tick M or F on each box while you draw.

  3. Count the asked group from the drawing, not from memory.

Why it works:

Counting boxes never misses anyone twice; counting from memory usually does.

Try this

A family has a couple, their 3 sons, and 2 daughters of each son. No one else is in the family. How many female members are there?

Show solution

  1. Females: the wife, that is 1.

  2. Granddaughters: 3 times 2, that is 6.

  3. Total females: 1 + 6.

Answer

7 female members

Type 5common

Mother's side and father's side

How to spot it:

The chain passes through the mother or the father: 'mother's father', 'father's sister', 'maternal uncle'.

Method

  1. Trace one link at a time and draw one arrow per link.

  2. Through the mother = maternal. Through the father = paternal.

  3. Count arrows for the generation, then fix the word with the gender.

Why it works:

A long word only packs three facts: which side, how many arrows, which gender.

Try this

B is the father of A's mother. How is B related to A?

Show solution

  1. A's mother: one arrow up from A.

  2. Her father: one more arrow up, and male.

  3. Two arrows up through the mother's side.

Answer

Grandfather (maternal grandfather)

08

Formula sheet

Mirror pairs
father↔son, uncle↔nephew\text{father} \leftrightarrow \text{son},\ \text{uncle} \leftrightarrow \text{nephew}

Every relation has a mirror. If A is B's uncle, B is A's nephew or niece.

Marriage words
child’s spouse→son/daughter-in-law\text{child's spouse} \to \text{son/daughter-in-law}

Spouse's parent = father/mother-in-law. Sibling's spouse or spouse's sibling = brother/sister-in-law.

Cousin
cousin=child of a parent’s sibling\text{cousin} = \text{child of a parent's sibling}

An uncle's or aunt's child is always a cousin, never a nephew.

09

Shortcuts that save time

⚡ Write each sentence as an arrow

In the margin, turn every sentence into an arrow: 'Suresh's daughter is Pooja' becomes Suresh to Pooja (F). When every sentence is an arrow, the tree draws itself.

Example

A is B's sister. C is A's mother. How is C related to B?

Show solution

  1. Arrows: C to A (F).

  2. A and B sit on one row, so C is above B too.

  3. C is one arrow above B.

Answer

Mother

⚡ Flip the word, not the tree

One tree answers both directions. Keep the drawing, swap to the mirror word: father goes to son, uncle to nephew, grandfather to grandson.

Example

X is Y's grandmother. How is Y related to X?

Show solution

  1. Tree: X is two arrows above Y.

  2. Asked from X's side, going down.

  3. Two arrows down, gender of Y decides the word. Y's gender is not fixed.

Answer

Grandson or granddaughter: cannot be determined

10

Mistakes to avoid

Where most students lose marks on this subtopic.

Mistake 01

Giving a gender no word stated, like calling every cousin 'he'.

Mark M or F only from gendered words. Leave the rest blank and let the blank decide the option.

Mistake 02

Answering the reverse direction: 'grandfather' when asked how the elder relates to the child.

Start from the person named after 'related to'. Then walk to the other person.

Mistake 03

Calling an uncle's child a nephew.

Uncle's or aunt's child is a cousin. Nephew is a sibling's child.

Mistake 04

Reading 'only son' as 'only child'.

'Only son' leaves room for sisters. 'Only child' leaves no sibling at all.

Mistake 05

Putting a married couple on different rows.

A couple always shares one row, one generation.

11

Quick revision

Read this the night before the exam.

  • Draw the tree every time. Never hold a chain in your head.

  • Gender comes only from gendered words. Blank stays blank.

  • 'How is A related to B?' means name A from B's side.

  • One arrow = one generation. Two up = grandfather, two down = grandson.

  • Parent's sibling = uncle or aunt. Their child = cousin. Sibling's child = nephew or niece.

  • Only son is not only child. Read the exact word.

  • A blank gender plus 'Cannot be determined' in the options is usually the answer.

12

Practice: 12 questions

Sets of 10, mixed across the question types above. Every answer has a step-by-step explanation.

Topic test · 12 questions

Suggested time 9 min · wrong answers go to your mistake notebook automatically.

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