No, the genetic combination of the mother does not play a significant role in determining the sex of a newborn. The sex of a child is determined by the sperm, specifically whether it carries an X or Y chromosome. The mother always contributes an X chromosome, while the father can contribute either an X or a Y.
Here’s why:
Mothers only contribute an X chromosome: All female eggs contain one X chromosome.
Fathers can contribute X or Y: Sperm can carry either an X or a Y chromosome.
Determining the sex: If a sperm carrying an X chromosome fertilizes the egg, the resulting child will be female (XX). If a sperm carrying a Y chromosome fertilizes the egg, the resulting child will be male (XY).