The father's sperm determines the baby's gender.
The sex of a baby is determined by the sex chromosomes, which are the X and Y chromosomes. Females have two X chromosomes (XX), while males have one X and one Y chromosome (XY). Therefore, a woman always contributes an X chromosome to the baby. According to the reference, "A man's X and a woman's X combine to become a girl, and a man's Y combines with a woman's X to become a boy."
The Role of the Father
The father's contribution is what decides the baby's sex because a man has both X and Y chromosomes. A sperm carrying an X chromosome will result in a female (XX), and a sperm carrying a Y chromosome will result in a male (XY). This means the father is the deciding factor in which chromosome is passed down and determines the baby's sex. While other genetic factors can influence the sex ratio, the fundamental principle remains: the sperm from the father is responsible for gender determination.
Father's Genetic Contribution
| Father's Sperm Chromosome | Mother's Egg Chromosome | Baby's Sex Chromosomes | Baby's Gender |
|---|---|---|---|
| X | X | XX | Female |
| Y | X | XY | Male |
Other Influencing Factors
- Although the father determines gender via the X or Y chromosome, it is worth noting that the reference also indicates other factors that affect the sex ratio. These include potential differences in the quantity of X and Y sperm produced by the father and other genetic factors that are not fully understood.
In summary, while the egg always contributes an X chromosome, the father’s sperm carries either an X or a Y chromosome, thus determining whether the child will be a boy or a girl.
