The standard explanation is that Fisher became bitter because he suffered serious injustice having his papers rejected by mathematicians who did not understand biology and biologists who did not understand mathematics.
Ang karaniwang paliwanag ay na Fisher ay naging mapait dahil siya suffered malubhang kawalan ng katarungan sa pagkakaroon ng kanyang mga papeles tinanggihan ng mga mathematicians na hindi maintindihan biology at biologists na hindi maintindihan matematika.