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What Are First and Second Cousins?

Michele Meleen
Family tree infographic

While it is possible to refer to a number of extended family members simply as "cousins," you might find yourself wondering "Exactly what are first and second cousins?" Use simple cousin charts to help you better understand geneaology terms like "first cousins," "second cousins," and "first cousins once removed."

Who Are Considered First Cousins?

First cousins share a grandparent, either maternal or paternal. The children of your uncles and aunts are therefore your cousins, or first cousins. If members of your family were adopted, then your first cousins might not be blood related to you.

Family tree depicting first cousins
You and Michelle are first cousins.

First Cousin Example Family

The easiest way to understand the relationships between cousins is with a hypothetical example. This illustration keeps the family tree as simple as possible, ignoring most siblings and the extended families of spouses who have married into the reference family. With this hypothetical example, you and Michelle are first cousins because you have the same grandparents.

  • Your maternal (mother's) grandmother and grandfather had two children: your mom and Danny.
  • Your mom went on to marry your dad and have you.
  • Danny went on to marry Pam to have Michelle.
  • You and Michelle are first cousins.

Who Are Second Cousins?

Second cousins share a great-grandparent, either maternal or paternal. You and your second cousins have the same great-grandparents, but not the same grandparents. Understanding second cousins is much the same as understanding first cousins, except the family tree must go back one further generation. If members of your family were adopted, your second cousins may not be blood related to you.

Family tree depicting second cousins
You and Ashley are second cousins.

Second Cousin Example Family

With this hypothetical example, you and Ashley are second cousins. This is because the closest common ancestor that you share is your great-grandma. Ashley's grandpa, your great-uncle, is your grandma's brother.

  • Your grandmother has a brother who is your great-uncle.
  • Your grandma and great-uncle were born to your great-grandmother and your great-grandfather.
  • Your great-uncle (sometimes referred to as a grand-uncle) married your great-aunt (sometimes referred to as a grand-aunt) and they had a daughter named Vivian.
  • Vivian married Philip and had a daughter named Ashley.
  • You and Ashley are second cousins.

What Does "Once Removed" Mean With Cousins?

In addition to the distinction between first cousins and second cousins, there is also the added designation of being "once removed." Being a "once removed" cousin means there is one generation separating you and your cousin. This could be one generation above yours or one generation below yours.

First Cousin Once Removed Chart

Since you and your first cousins, by definition, are all from the same generation, you wouldn't use the term "once removed" for your true first cousin relationships. You would, however, use the term "first cousin once removed" to describe your relationship to your parents' first cousins. You could also explore the family tree in the other direction and your first cousin's child would be your first cousin, once removed.

  • Your mom and Vivian are first cousins.
  • You and Vivian are one generation apart.
  • Vivian is your first cousin, once removed.
First cousins once removed chart
You and Vivian are first cousins once removed.

Second Cousin Once Removed

To find a second cousin, once removed, use the same logic. Your mom or dad's second cousin would be someone they share great-grandparents with. Your mom's second cousin or your dad's second cousin would be your second cousin, once removed because your parents are one generation older than you. If you move down a generation, your second cousin's child would be your second cousin, once removed.

What Does "Twice Removed" Mean With Cousins?

Since "removed" denotes the number of generations between you and a relative, "twice removed" means there are two generations separating you and your cousin. This could mean two generations above you or two generations below you.

First Cousin Twice Removed Chart

Since you and your first cousins are from the same generation, you wouldn't use the term "twice removed" to describe them. You would use the term "first cousin, twice removed" to describe your relationship to your grandparent's first cousins or to the grandchildren of your true first cousins.

  • Your grandma and Great Uncle Bob are first cousins because they share the same grandparents.
  • Great Uncle Bob is two generations older than you.
  • You and Great Uncle Bob are first cousins, twice removed.
First cousin twice removed chart
You and Great-Uncle Bob are first cousins twice removed.

Second Cousin Twice Removed

Using the same First Cousin Twice Removed chart, you can extrapolate the family tree to see that if your great-great-grandma had a sister, her daughter's daughter would be your grandma's second cousin and your second cousin, twice removed. Alternatively, your second cousin's grandchild would be your second cousin, twice removed if you went down the family tree.

Determining Types of Cousins

The terminology used to describe the relationship between cousins can be further extended to reflect as many generations as needed including third cousins, fourth cousins, and so on. Cousins can also be related by blood or by marriage. To determine if you're cousins by blood, you'll need to know who birthed each family member to follow the blood line.

  • First cousins share a common grandparent.
  • Second cousins share a common great-grandparent.
  • Third cousins share a common great-great-grandparent (the grandparent of a grandparent).
  • Fourth cousins share a common great-great-great-grandparent (the grandparent of a great-grandparent).
  • Cousins who are thrice removed are three generations apart.

Can Cousins Get Married?

Cultural norms and laws vary from state to state in the U.S. and from country to country about whether first or second cousins can get married. Marrying a second cousin is legal in the U.S., but most U.S. states don't allow legal marriages between first cousins. While marrying a first cousin doubles your risk of having a baby born with a birth defect, that percentage is really only a 4-6% chance. Second cousins who have children together have no more risk of having a child with a birth defect than any other unrelated couple.

Keep Track of Your Cousins

Track your cousins as far back as desired by starting to make a family tree. You can purchase family tree software or use a free family tree template to draw your own family tree. You might be surprised who you discover you're related to when creating family archives. For example, it was revealed in 2007 that Dick Cheney and Barack Obama are actually related - they're eigth cousins, albeit only by marriage.

What Are First and Second Cousins?