Traits, such as hair or eye color, are determined by the proteins produced by cells in our body. These proteins are encoded by our genes, which are segments of DNA that carry instructions for making these proteins. Different versions of genes, called alleles, can result in variations in traits. For instance, a gene for hair color may have different alleles for blonde, brown, or black hair. The proteins made by our cells, as directed by our genes, determine the physical characteristics we inherit and display.
