Skip to content

Quantitative Aptitude · Blood Relations

Introduction to Blood Relations for CA Foundation

Updated 1 October 2026

Blood relation problems give you a few statements about how people in a family are connected. You must work out how two people are related. Learn the basic family terms, separate paternal (father's) and maternal (mother's) sides, draw a small family tree, and read the statements one at a time.

Understand Introduction to Blood Relations

A blood relation question describes people in a family using relationship words like father, sister or uncle. You are then asked how one person is related to another. It is a logical reasoning topic in Paper 3. You need no formula, only clear thinking and careful reading.

Start with the basic terms. Your father and mother are your parents. Their parents are your grandparents. Your parents' children are your brother or sister (siblings). Your father's or mother's brother is your uncle. Your father's or mother's sister is your aunt. The children of your uncle or aunt are your cousins. Your spouse's parents are your parents-in-law.

Next, separate the two sides. The paternal side is your father's family. The maternal side is your mother's family. So a paternal uncle is your father's brother, and a maternal uncle is your mother's brother. Likewise a paternal grandfather is your father's father, and a maternal grandfather is your mother's father. Exam questions often use the word 'uncle' alone, which can mean either side unless the question says more.

The next idea is gender. Some words tell you the gender: father, mother, brother, sister, son, daughter, uncle, aunt, nephew, niece. Others do not: child, parent, sibling, cousin, spouse. A name like 'Ravi' or 'Sita' also hints at gender, but only treat it as fact when the question says so. If gender is unknown, the answer may be 'cannot be determined'.

Finally, think in generations. Parents are one generation above you. Grandparents are two above. Your children are one below. Siblings and cousins are in your own generation. Tracking the generation helps you check whether your answer is sensible.

Key formulas to remember

Parent's brother
Father's brother = paternal uncle; Mother's brother = maternal uncle
Both are usually called 'uncle'. The side matters only if the question asks for it.
Parent's sister
Father's sister = paternal aunt; Mother's sister = maternal aunt
The husband of an aunt is also called uncle.
Grandparents
Parent's father = grandfather; Parent's mother = grandmother
Father's parents are paternal grandparents. Mother's parents are maternal grandparents.
Children of siblings
Brother's or sister's son = nephew; daughter = niece
Your cousin is the child of your uncle or aunt, not your sibling.
In-law relations
Spouse's father = father-in-law; spouse's mother = mother-in-law; spouse's brother = brother-in-law; sister's husband = brother-in-law
Brother-in-law has more than one meaning. Read the context.
Gender-neutral terms
Child, parent, sibling, cousin, spouse = gender not given
Do not assume a gender unless the question states it or a gendered word fixes it.

How to solve Introduction to Blood Relations questions

Use this method for any introductory blood relation question. Go slowly on the first read, because most errors come from misreading one word.

  1. 1Read the whole question once and note what is being asked, such as 'How is A related to B?'.
  2. 2Break the information into short statements, one relationship each.
  3. 3Mark the gender of each person wherever a word or the question gives it. Leave unknown genders blank.
  4. 4Draw a simple family tree. Put the older generation at the top, and use a line for marriage and a vertical line for children.
  5. 5Add each statement to the tree in order, starting with the one that names a clear person.
  6. 6Mark paternal and maternal sides if the question uses words like uncle, aunt or grandparent.
  7. 7Trace the path from the first person to the second and convert it into a single relationship word.
  8. 8Check the answer against the options and confirm the gender and generation are consistent.

Quickest way: Short-path method for MCQs

When to use it: Use it when the question has two or three simple statements and four options, and you want to save time.

  1. Pick the person the question asks about and write only that person's initial.
  2. Write the chain in short form, such as A → father → B → sister → C.
  3. Reduce the chain one link at a time: father's sister = paternal aunt.
  4. Find the option that matches the reduced relation and eliminate options of the wrong gender or generation.
  5. If the gender is not fixed by the question, pick 'cannot be determined' only if no option fits every possible case.
  6. Skip a question if the family tree has more than five people and you are stuck after one minute, because wrong answers cost 0.25 marks.

Common mistakes in Introduction to Blood Relations

  • Assuming a gender from the name or from a neutral word like 'cousin' or 'child'.

    Students want a definite answer and fill in the missing detail from habit.

    Fix: Treat gender as known only if the question or a gendered word says so. Otherwise look for an option like 'cannot be determined'.

  • Mixing up paternal and maternal sides.

    The words sound alike and students read quickly.

    Fix: Remember: paternal = pa = father's side. Maternal = ma = mother's side. Write P or M beside the person in your tree.

  • Calling a cousin a brother or sister.

    Everyday speech often does this, but exam logic does not.

    Fix: A sibling shares the same parents as you. A cousin is the child of your parent's sibling.

  • Confusing 'father's sister' with 'mother's sister' as the same relation.

    Both are called aunt, so the difference seems small.

    Fix: Both are aunts, but the answer options may separate paternal and maternal. Keep the side as long as the question needs it.

  • Reading 'A's father's son' as always meaning a brother.

    Students overlook that the answer depends on whether A is male or female.

    Fix: A's father's son is A's brother if A is female. If A is male, it may be A himself or his brother.

  • Getting the direction of a relation wrong, such as saying 'A is the father of B' when the chain says B is the father of A.

    Students read 'A is B's father' and 'A's father is B' as the same.

    Fix: Say each statement aloud in the form 'X is the ___ of Y' and draw an arrow from the older generation to the younger.

Worked examples

Example 1

Pointing to a man, Rita says, 'He is the son of my father's only brother.' How is the man related to Rita? (a) Brother (b) Paternal cousin (c) Maternal uncle (d) Nephew

Show the solution
  1. Rita's father's only brother is Rita's paternal uncle.
  2. The son of that uncle is the child of Rita's paternal uncle.
  3. Child of a parent's sibling is a cousin.
  4. The man is male and on the father's side, so he is a paternal cousin.

Answer: (b) Paternal cousin

Example 2

A says, 'B is the brother of my mother.' How is B related to A? (a) Paternal uncle (b) Maternal uncle (c) Father-in-law (d) Grandfather

Show the solution
  1. A's mother is a parent on the maternal side.
  2. B is her brother, so B is a brother of A's mother.
  3. A mother's brother is called a maternal uncle.
  4. Options (a), (c) and (d) do not match: a paternal uncle is a father's brother, a father-in-law is a spouse's father and a grandfather is a parent's father, so none of them matches 'mother's brother'.

Answer: (b) Maternal uncle

Example 3

Meena is the daughter of Suresh. Suresh is the son of Kamal. Anil is the son of Kamal. How is Anil related to Meena? (a) Father (b) Paternal uncle (c) Maternal uncle (d) Grandfather

Show the solution
  1. Meena is Suresh's daughter. Suresh is Kamal's son.
  2. So Kamal is Meena's grandfather on her father's side.
  3. Anil is also Kamal's son, so Anil and Suresh are both Kamal's children. Anil is Suresh's brother.
  4. Suresh is Meena's father, so Anil is Meena's father's brother.
  5. A father's brother is a paternal uncle. Option (a) is wrong because Meena's father is Suresh. Option (c) is wrong because Anil is on the father's side, not the mother's. Option (d) is wrong because Kamal, not Anil, is the grandfather.

Answer: (b) Paternal uncle

Exam tips

  • Draw a tiny family tree even for easy questions. It takes ten seconds and prevents mistakes.
  • Watch the words 'only', 'eldest' and 'youngest'. They can change the answer.
  • Check each option's gender before comparing relations. This often removes two options quickly.
  • Do not assume a gender from a name. Use the question's words.
  • If a question has a long chain and you are unsure, skip it. A wrong answer costs 0.25 marks.

Practice questions from Blood Relations

Introduction to Blood Relations: frequently asked questions

What is a blood relation problem in logical reasoning?

It is a question where you are given statements about family members and asked how two people are related. You solve it by drawing a family tree and following the statements.

What is the difference between paternal and maternal?

Paternal refers to the father's side of the family. Maternal refers to the mother's side. For example, your father's brother is a paternal uncle and your mother's brother is a maternal uncle.

Do I need to memorise formulas for blood relations?

No formulas are needed. You only need to know the family terms and what each means, such as uncle, aunt, cousin, nephew and niece.

How is a cousin different from a sibling?

A sibling is a brother or sister who shares your parents. A cousin is the child of your uncle or aunt.