The theory of the branching process (also a part of the stochastic process) was developed with the aim of understanding the extinction probabilities of family surnames that transfer between generations through male offspring. Males carry their family’s surnames in England and Francis Galton wanted to study the probabilities of extinction of family surnames in medieval England based on the number of male offspring that a couple has in each generation. The field of branching process could have originated from studies on son preference in demography, where financial assets and surnames were passed down through sons in medieval England.