A marriage of a Negro male (AABB) to a white (aabb) female results in mulatto offspring in the F1 lineage. Intermarriage between mulatto (AaBb) offspring in the F1 lineage resulted in F2 offspring with 1 Negro, 4 Dark, 6 Medium, 4 Light, and 1 White.
here,
Genotype of Negro male is AABB
The genotype of the white female is aabb
First progeny is F1 and second progeny is F2
Parents : ♂ × ♀
Phenotype: Negro male white female
Genotype : AABB aabb
Gamit : (AB) (ab)
F1 breed : AaBb (mulatto)
Self fertilization : F1×F1
Parents : ♂ × ♀
Phenotype: mulatto mulatto
Genotype : AaBb AaBb
Gamit : (AB)(Ab)(aB)(ab) (AB)(Ab)(aB)(ab).
F2 progeny (checker board)
Remarks : From the checker board, out of 16 children, 1 is Negro, 4 are dark, 6 are medium, 4 are light and 1 is white. In this case, the skin color has become darker as the number of expressed genes increases.
Phenotypic Ratio : Negro : Dark : Medium : Light : White = 1:4:6:4:1