side then it has a probability mass function given by: \rho_Y(y) = \begin{cases}\frac{1}{2},& \text{if }y=1,\\ \frac{1}{2},& \text{if }y=0.\end{cases} Homology (biology) A homologous trait is any characteristic of organisms that is derived from a common ancestor . This is contrasted to analogous traits: similarities between organisms that were not in the last