I thinking the answer was for some genes, both alleles express together. Others combine to give an average phenotype....
A master's degree<span> in orthotics and </span>prosthetics<span> is required to work as a </span>prosthetist<span>, along with a 1-year residency. During this </span>education<span> and </span>training<span>, students learn about various types of devices and get clinical experience. After completing these requirements, they </span>can<span> take the national certification exam.</span>