What do the genes responsible for skin color indicate?

In a polygenic trait,an individual with three recessive alleles expresses $50 \%$ of the trait,while an individual with three dominant alleles expresses $80 \%$ of the trait. What is the contribution of each dominant allele to the trait (in $\%$)?

Who provided the first experimental evidence for the polygenic concept of inheritance?

Polygenic inheritance in humans is represented by ....

The grain color in wheat is controlled by three pairs of polygenes. When a red-grained wheat variety is crossed with a white-grained variety,an $F_1$ hybrid is produced. When the $F_1$ hybrid is self-pollinated,what fraction of the $F_2$ generation will resemble the parental phenotypes?

$A$ polygenic trait is controlled by $3$ genes $A, B$,and $C$. In a cross $AaBbCc \times AaBbCc$,the phenotypic ratio of the offspring is observed as $1:6:x:20:x:6:1$. What is the possible value of $x$?