Consanguinity: Coefficients of Inbreeding and Relationship (Wright)
Inbreeding and relationship coefficients for a related couple by Wright's path rule, with the recessive risk to a child.
Open the calculator → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- Relationship
- First cousins
- Allele frequency of a recessive condition
- 0.01
Result: First cousins: inbreeding coefficient of the child F = 1/16; coefficient of relationship of the couple r = 1/8.
The tool opens with these values already filled in. Replace them with your own.
What you enter
- Relationship
- Own paths, one per common ancestor: generations from each partner
- Allele frequency of a recessive condition (optional)
How this is calculated
Citation
Wright S. Coefficients of inbreeding and relationship. Am Nat 1922;56:330-338 (read in the public-domain copy at archive.org): F as the sum over paths of one half to the power n + n' + 1. Read the source ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.