Module 01
Punnett Simulator
Choose a trait, set each parent's genotype, and read the cross.
Trait
Parent A
Parent B
B
b
B
BB
Bb
b
Bb
bb
Genotypic ratio
Bb2/4 · 50%
BB1/4 · 25%
bb1/4 · 25%
Phenotypic ratio
Brown eyes75%
Blue eyes25%
Mendel's Law of Segregation: each parent passes one of two alleles at random. With a heterozygous × heterozygous cross you'll see the classic 3:1 phenotypic ratio.