Malecot's method of coancestry

Malecot's coancestry coefficient, $$f$$, refers to an indirect measure of genetic similarity of two individuals which was initially devised by the French mathematician Gustave Malécot.

$$f$$ is defined as the probability that any two alleles, sampled at random (one from each individual), are identical copies of an ancestral allele. In species with well-known lineages (such as domesticated crops), $$f$$ can be calculated by examining detailed pedigree records. Modernly, $$f$$ can be estimated using genetic marker data.