We inherit 23 chromosomes from our mother and another 23 chromosome pairs from our father. You have to inherit a defective chromosome for you to get the mutation. This is what is called germ line mutation usually carried in the sperm or ovum. Of the 23 chromosomes, 22 are autosomal and 1 is chromosomal meaning of the 23 one of them is X and another one is . You get the Y from your father and the X from your mother.
