An organism can't chose to have a mutation because it depends on the way they are born. If they are missing some type of mineral, (Protein, Vitamin, etc.) they will have a mutation because they're missing that. Well, something similar to a mutation is natural selection and genes. For example, there are some short and tall giraffes. The tall ones can reach the tree and the short ones can't so they die and the tall ones can reproduce and their offspring will inherit that trait
