This is what I found off google idk if this is helpful or not but here ya go. F1 Generation Definition. The F1 generation refers to the first filial generation. Filial generations are the nomenclature given to subsequent sets of offspring from controlled or observed reproduction. ... The first set of offspring from these parents is then known as the F1 generation. And this The offspring resulting from a parental cross are referred to as the first filial generation (or F1 generation). The F1 generation is the generation resulting immediately from a cross of the first set of parents (parental generation).