Is broad-sense heritability just the slope of the line that passes through the coordinates:
- (1, The phenotypic correlation among monozygotic twins)
- (0.5, The phenotypic correlation among dizygotic twins
- [Optionally] (0, The phenotypic correlation among unrelated individuals)?
Here, the X axis is the relatedness (0 for unrelated, 0.5 for dizygotic, and 1 for monozygotic) and the Y axis is the correlation coefficient r. Is this the same as twin-based broad-sense heritability?
(This would also mean you can estimate heritability by taking the slope of the line through only dizygotic siblings, as they don't always share 50/50 of their DNA and there will be some spread in the X dimension.)