fire x sulfer make a black eyed lucy, breed it to a normal, you only make fires or sulfers, no black eyed lucy or normals. unlike say if you had a bumblebee and breed it to a normal, then you could make bumblebees, pastel, spider, and normal.

same for black pastel and cinny, they make an 8 ball, 8 ball to a normal only make black pastels and cinnys.

the allele stuff when combo'd is homozygous, its not exactly the same gene, but still on the same allele.