How to Quickly Estimate Heritability from Twin Studies (Falconer's Formula)

In this video I explain how to quickly estimate heritability using concordance rates from monozygotic and dizygotic twin studies.

This technique, known as Falconer's Formula, simply multiplies the difference between same-sex MZ and DZ concordance rates by 2 to estimate the overall role of genes on the trait or behavior. Next I provide data from 2 research examples to practice the technique, using the Kendler et al (2006) study of depression in Swedish twins, and the Stunkard et al (1990) study of body mass in twins.

This approach doesn't address additive and non-additive genetic effects, and has a tendency to overestimate the role of genes, but provides a rough estimate of the heritability for a trait, which can serve as a useful point of comparison with other studies and approaches.

For more details on twin approaches to heritability, see:
Estimating Heritability from Twin Studies

Kendler et al (2006) example:

Stunkard et al (1990) example:

[brunolevilevi]

Falconers formula uses correlation, not the concordance rates. How do I get correlation from concordance rates?

[glebmixaylovich]

Thank you for your explanation, What does it mean if heritability calculated by Falconer's Formula is > 1 (or > 100%)?