Here's how it works:
* Humans have two sex chromosomes: X and Y.
* Females have two X chromosomes (XX).
* Males have one X and one Y chromosome (XY).
During fertilization, the mother always contributes an X chromosome from her egg cell. The father, however, can contribute either an X or a Y chromosome from his sperm cell.
Therefore:
* If the sperm cell carries an X chromosome, the offspring will be female (XX).
* If the sperm cell carries a Y chromosome, the offspring will be male (XY).
In essence, the father's sperm cell determines the sex of the offspring.
It's important to note that this is a simplified explanation. There are some rare genetic conditions that can influence sex determination, but the X and Y chromosomes are the primary factors.
