 All diploid organisms with allosome-determined sex get half of their allosomes from each of their parents.In mammals, females are XX, they can pass along either of their X's, and since the males are XY they can pass along either an X or a Y.For a mammal to be chromosomally female, the individual must receive an X chromosome from both parents, whereas to be chromosomally male, the individual must receive a X chromosome from their mother and a Y chromosome from their father.