Alleles are variant forms of the same gene. Since genes contain the information needed to synthesize different proteins, alleles too carry the information needed to synthesize different versions of the same protein. This can have several significant effects within the body. Alleles influence an individual’s genotype or genetic makeup. This plays a pivotal role in shaping an individual’s physical traits and features such as how the individual looks, the color of their eyes, and the texture of their hair. Alleles also influence an individual’s risk factors for developing certain diseases or allergies as well as how the individual will react to different medications.