Exactly, aamiller.
Every celled organism on this planet, has the very same DNA building blocks. A "Gene Tool Box", geneticist are saying to the laymen. It just depends on the gene mutation in even a single, particular strand, that can change a cell from being a flipper to becoming a hand.
If there was no evolution, then could someone explain genetic disorders to me?
In the process of "Handing down" DNA from adult to offspring—a mutation- while you were replicating yourself—then that would be evolution. Since the body naturally sheds it's older cells, and replaces them with regenerated cells, in it's place. There, in that minute instance, things in the core DNA can change. Why? There are several different factors to that, which are numinous. (I'd be happy to write them all down, if anyone asks).
I've worked very closely with my sister, who is a molecular biologist out of UCLA. She's done tons of work on genetic disorders and gene mutation and I've seen, the work done everyday to further the betterment of Humans and Animals alike.
I firmly believe in evolution, in gene manipulation, and it's furthering the our species.
As far as it contributing to Atheism? The theory and science of evolution doesn't make atheist of people. That is a personal choice, by someone, if they want to believe in something or not. There are plenty people of science, whom are very deep in their religion, and vice versa. That, isn't even a factor in either of the ideas.