Is skin color the only polygenic trait?

No, skin color is not the only polygenic trait. Many other human traits are also influenced by multiple genes, including height, weight, hair color, eye color, and disease susceptibility. Polygenic traits are determined by the combined effects of multiple genes, each of which contributes a small amount to the overall phenotype. The expression of polygenic traits can be complex and can be influenced by environmental factors as well as genetic variation.