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Sibling vs. Cousin: What's the Difference?

Edited by Aimie Carlson || By Janet White || Published on November 13, 2023
A sibling shares at least one biological or legal parent; a cousin is a child of one's aunt or uncle.

Key Differences

Siblings are individuals who share at least one biological or legal parent. Growing up, they often form bonds by living in the same household and experiencing shared familial and cultural influences. Cousins, however, are children of one's aunt or uncle, placing them one step removed in the familial lineage.
The relationship between siblings can be both harmonious and contentious, given the close quarters and potential for rivalry. Regardless, this bond is often deeply rooted due to shared formative experiences. In contrast, cousins may not spend as much time together but can still have a significant relationship, depending on familial closeness and individual circumstances.
Legally, siblings usually have more rights and responsibilities towards each other, especially when considering inheritance or guardianship matters. In many cultures, cousins are considered extended family, thus usually having less legal obligations towards one another compared to immediate family members.
Siblings may be of full relation, sharing both parents, or of half relation, sharing just one parent. Meanwhile, cousins can be first cousins, once removed, or even second or third cousins, depending on the shared ancestry's distance.
Despite their differences, both siblings and cousins play integral roles in one's life. They provide companionship, support, and shared history that can span from early childhood into adulthood.

Comparison Chart


Child of at least one shared parent
Child of one's aunt or uncle

Familial Proximity

Immediate family
Extended family

Shared Ancestors

One or both parents
Grandparents or further back

Legal Obligations

Typically more (e.g., inheritance)
Typically fewer


Can be full, half, step, or adopted
Can be first, second, once removed, etc.

Sibling and Cousin Definitions


One sharing only one parent.
My half-sibling is from my father's previous marriage.


Sharing one set of grandparents.
Our grandmothers are sisters, so we are first cousins.


One's brother or sister.
My sibling and I went to the same school.


Related through marriage, not blood.
My cousin by marriage joined our family celebrations.


Related due to a parent's remarriage.
I gained a step-sibling when my mom remarried.


One generation apart.
My mother's first cousin is my first cousin once removed.


Adopted into the family.
My adopted sibling and I are close.


Farther down the family tree.
We're third cousins, sharing great-great-grandparents.


One of two or more individuals having one or both parents in common; a brother or sister.


The child of one's aunt or uncle.
My cousin lives overseas.


A person who shares a parent; one's brother or sister who one shares a parent with.
None of my siblings are married yet.


A child of one's aunt or uncle. Also called first cousin.


(comptheory) A node in a data structure that shares its parent with another node.


A relative descended from a common ancestor, such as a grandparent, by two or more steps in a diverging line.


(taxonomy) The most closely related species, or one of several most closely related species when none can be determined to be more closely related.


A relative by blood or marriage; a kinsman or kinswoman.


A brother or a sister.


A member of a kindred group or country
Our Canadian cousins.


A person's brother or sister


Something similar in quality or character
"There's no mistaking soca for its distant Jamaican cousin, reggae" (Michael Saunders).


Related by blood.
My sibling and I resemble each other.


Used as a form of address by a sovereign in addressing another sovereign or a high-ranking member of the nobility.


The child of a person's uncle or aunt; a first cousin.
I think my cousin is a good man.


(archaic) A kinsman.


Any relation who is not a direct ancestor or descendant but part of one's extended family; one more distantly related than an uncle, aunt, granduncle, grandaunt, nephew, niece, grandnephew, grandniece, etc.


(obsolete) A title formerly given by a king to a nobleman, particularly to those of the council. In English writs, etc., issued by the crown, it signifies any earl.


(figurative) Something kindred or related to something else.


A member of the British intelligence services (from an American perspective) or of the American intelligence services (from a British perspective).


One collaterally related more remotely than a brother or sister; especially, the son or daughter of an uncle or aunt.
Thou art, great lord, my father's sister's son,A cousin-german to great Priam's seed.


A title formerly given by a king to a nobleman, particularly to those of the council. In English writs, etc., issued by the crown, it signifies any earl.
My noble lords and cousins, all, good morrow.


Allied; akin.


The child of your aunt or uncle


Can Cousins resemble each other?

Yes, especially if their parents are closely related siblings.

Do Siblings always share DNA?

Biological siblings share DNA; step or adopted siblings might not.

Can Siblings have different parents?

Yes, half-siblings share one parent; step-siblings might share no biological parents.

Is a cousin's child also a cousin?

They are a "first cousin once removed" from you.

Can Siblings have different last names?

Yes, due to reasons like marriage, adoption, or personal choice.

Do Siblings always grow up together?

Not always; they can be separated by circumstances, adoption, etc.

Can Siblings have different nationalities?

Yes, if born or naturalized in different countries.

Are Cousins immediate family?

Typically no, cousins are considered extended family.

How are Cousins twice removed related?

They're two generations apart, like your grandparent and their second cousin.

Can Siblings be of different ages?

Yes, siblings can range from close in age to many years apart.

Do all cultures view Sibling relationships the same way?

No, cultural norms and values shape sibling relationships differently.

Are Cousins' children also Cousins?

They're your "first cousins once removed."

Can Cousins become legal guardians?

Yes, depending on legal and familial circumstances.

Are Siblings always close emotionally?

Not always; relationships vary based on individual and family dynamics.

Can Cousins be as close as Siblings?

Yes, relationship closeness depends on individual and family dynamics.

How distant can Cousins be and still be related?

There's no limit, but the shared ancestor may be many generations back.

Is the bond between Siblings biological?

It can be, but bonds with step or adopted siblings are social and emotional.

Who's closer in relation, Sibling or Cousin?

Siblings are immediate family, while cousins are extended family.

Are Cousins' siblings to each other?

No, they're siblings to their own brothers and sisters, not to each other.

Can you have more than one Sibling?

Yes, you can have multiple brothers and sisters.
About Author
Written by
Janet White
Janet White has been an esteemed writer and blogger for Difference Wiki. Holding a Master's degree in Science and Medical Journalism from the prestigious Boston University, she has consistently demonstrated her expertise and passion for her field. When she's not immersed in her work, Janet relishes her time exercising, delving into a good book, and cherishing moments with friends and family.
Edited by
Aimie Carlson
Aimie Carlson, holding a master's degree in English literature, is a fervent English language enthusiast. She lends her writing talents to Difference Wiki, a prominent website that specializes in comparisons, offering readers insightful analyses that both captivate and inform.

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