Get notified of page updates
How Are Mutations Inherited?
Learn how gene mutations can lead to cancer, what types of cancer may be hereditary and how parents can pass inherited mutations to their children.

Stay up to date on research and information

Sign Up for FORCE Newsletters

Hereditary Cancer and Genetic Testing > Hereditary Cancer > How Are Mutations Inherited?

Glossary on

How Mutations Are Inherited

People can pass an inherited gene mutation to their children through their sperm or eggs. When a person with a gene mutation has children, each child has a 50 percent chance of inheriting the same mutation.  

Genetics experts look carefully at a family’s medical history for signs of . You can assist them by gathering medical information from relatives on both sides of your family.

Typically, a genetics expert will look at three or more generations of a family’s medical history to help predict whether family members are likely to have an . They will use this information to create a medical family tree known as a pedigree. 

Degrees of relatedness

When speaking about a family tree, experts use the term “degree of relatedness” to describe how closely related one family member is to another. "First-degree relatives” share half of their . If a person has an , each of their first degree relatives has a 50 percent chance of testing positive for the same mutation. Second-degree relatives share one fourth of their , third-degree relatives share one eigth of their , and so on. 

  • First-degree relatives
    • SiblingsPicture of a sample pedigree
    • Children
    • Parents
  • Second-degree relativesHalf-siblings
    • Uncles and aunts
    • Grandparents
    • Grandchildren
    • Nieces and nephews
  • Third-degree relatives
    • Cousins
    • Great grandparents
    • Great-aunts and Great-uncles
Last updated January 31, 2022