Female babies are made when a mother's X chromosome combines with an X chromosome from the father's sperm.
How Sex Determination Works
The sex of a baby is determined by the chromosomes they inherit from their parents.
- Mothers always contribute an X chromosome.
- Fathers can contribute either an X chromosome or a Y chromosome.
| Father's Sperm Chromosome | Mother's Chromosome | Resulting Baby's Chromosomes | Baby's Sex |
|---|---|---|---|
| X | X | XX | Female |
| Y | X | XY | Male |
Role of the Father
It's important to emphasize that the father's sperm determines the sex of the baby. If the father contributes an X chromosome, the baby will be female. If the father contributes a Y chromosome, the baby will be male. This process is explained in the reference which states that "An X chromosome combines with the mother's X chromosome to make a baby girl (XX)..."
