The coefficient de parente $\sigma(x, y)$ of Malecot, which measures the genealogical relatedness of individuals $x$ and $y$, is derived as a correlation coefficient of certain genotype scores. An explicit formula is given for $\sigma(x, y)$ involving path sums in the ancestral charts of $x$ and $y$. The expected value of $\sigma(x, y)$ is worked out for certain random population models.
"An Index of Genealogical Relatedness Derived from a Genetic Model." Ann. Probab. 1 (5) 758 - 771, October, 1973. https://doi.org/10.1214/aop/1176996844