How is the sex of a child determined in human beings?

In humans, the males have 'XY' chromosomes and females have 'XX' chromosome as sex chromosomes. Therefore, 50% male gametes have X chromosome and other 50% have Y chromosome. The females have all gametes with X chromosome. The sex of the child is determined at the time of fertilization. If male gamete with X chromosome fertilizes with female gamete, it leads to a female child whereas if a gamete with Y chromosome fertilizes with female gamete, it leads to a male child.