If the egg fuses with a Y chromosome-bearing sperm, the child produced is a female.
What will be the sex of the child born :
(a) if X chromosome carrying sperm fertilizes an ovum containing X chromosome?
(b) if Y chromosome carrying sperm fertilizes an ovum containing X chromosome?
The sperms bearing X chromosome reach the egg faster than the sperms bearing Y chromosome.
The male gamete with Y chromosome fuses with a female gamete to form a zygote. The offspring will be a male child.