FIGURE 3.2
Determining a Zygote’s Sex Any given couple can produce four possible combinations of sex chromosomes; two lead to female children and two to male. In terms of the future person’s sex, it does not matter which of the mother’s Xs the zygote inherited. All that matters is whether the father’s Y sperm or X sperm fertilized the ovum. However, for X-linked conditions it matters a great deal because typically one, but not both, of the mother’s Xs carries the trait.