The phenotypic ratio 9:7 obtained in F2 generation instead of 9:3:3:1 is due to complementary genes. I didn't understand that statement. Could someone explain?

Question

The phenotypic ratio 9:7 obtained in F2 generation instead of 9:3:3:1 is due to complementary genes.  I didn't understand that statement. Could someone explain?

anonymous · Answer

in this type of gene interaction when both alleles have a dominance gene then they give a certain phenotype independently of phenomenon of homo or heterozygous condition...

see-
AAZZ, AAZz AaZz, AaZZ all will produce a similar phenotype bt in normal cross there were different phenotypes...

anonymous · Answer

oh. so complementary genes are genes that have at least one dominant allele?