Complex Inheritance

Mechanism

Complex inheritance means that many factors, usually a combination of genes and environment, are involved in causing a health problem or trait. These types of traits often occur in multiple family members because families share environmental and genetic factors. Most common, chronic diseases such as heart disease and diabetes are complex, as are many non-disease traits, including height. The chance of developing a complex trait depends on several factors, including:

  • The number of relatives affected with a condition (or related conditions)
  • How closely one is related to the affected individual(s)
  • Similarity of the shared environment
  • The location of disease or body system involved
  • Severity of the condition in the affected relative
  • The age at onset in the affected family member
  • The sex of the affected family member

Pedigree