Here is a quotation from this wikipedia page
The relatedness parameter (r) in Hamilton's rule was introduced in 1922 by Sewall Wright as a coefficient of relationship that gives the probability that at a random locus, the alleles there will be identical by descent. Subsequent authors, including Hamilton, sometimes reformulate this with a regression, which, unlike probabilities, can be negative.
Here is my question:
- What are all the different definitions of relatedness in biology?
- how do we calculate them?
- what do they mean?