Compute Wright's F = Σ (1/2)^(n1+n2+1)(1+F_A) over common-ancestor paths, with reference values (full sib 0.25, half sib 0.125, first cousins 0.0625) and elevated recessive risk q² + F·q·(1−q). Derived from Wright 1922, Falconer & Mackay, Hartl & Clark 2007, StatPearls. Educational use only.
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Key facts
Category
Education
Input types
select, number, textarea
Output type
json
Sample coverage
4
API ready
Yes
Overview
Calculate Wright's inbreeding coefficient F from one or more common-ancestor paths, then estimate recessive affected-offspring risk using the disease allele frequency q. The calculator is intended for genetics education and pedigree analysis, not clinical decision-making.
When to use
When checking Wright's F for a relationship represented by known common-ancestor paths.
When comparing a pedigree result with reference values such as 0.25 for full siblings, 0.125 for half siblings, or 0.0625 for first cousins.
When illustrating how inbreeding changes recessive affected-offspring risk relative to the random-mating baseline q².
How it works
1Choose single-path mode for one common ancestor or multiple-path mode to sum contributions from several paths.
2Enter the generations from the sire and dam to each common ancestor, along with the ancestor's own inbreeding coefficient F_A when applicable.
3Provide the recessive disease allele frequency q and select the number of decimal places.
4The result reports Wright's F, the path count, affected-offspring risk q² + F·q·(1−q), and the risk multiplier relative to q².
Use cases
Verify pedigree exercises in population genetics or animal breeding courses.
Compare coefficients for half-sibling, full-sibling, and first-cousin relationships.
Demonstrate how allele frequency and inbreeding coefficient affect recessive risk estimates.
Examples
1. Calculate F for full-sibling mating
Genetics student
Background
A coursework pedigree shows two individuals who share both parents as common ancestors.
Problem
Calculate the combined contribution of the two independent 1,1 paths and estimate recessive risk at q = 0.01.
How to use
Select multiple-path mode, enter two lines of "1, 1, 0", set the allele frequency to 0.01, and use six decimal places.