4. Examine the genotypes shown, there is a pattern that explains why polygenes are called "ADDITIVE." What is
the pattern?

The question above is related to the family's genotypes shown in the image below.

The pattern that explains the existence of polygens being called "additives" is the pattern of dominant and recessive genes incorporated in the same system.

Explanation:

Human skin color is determined by polygenic inheritance, as skin color is determined by two pairs of alleles, rather than just a pair of alleles, like most phenotypic characteristics. In this type of inheritance, it is common to use the term "polygenes" to determine the gene that is a gene that controls a phenotypic characteristic along with many other genes.

When "polygenes" are called "additives" it means that this set of genes are establishing a pattern of dominance and recessivity simultaneously in the same phenotypic characteristic, and may present extreme phenotypic differences, as in the case of the family shown below.