What type of sex determination is observed in humans? Explain.

(N/A) Humans possess $23$ pairs of chromosomes,out of which $22$ pairs are autosomes,which are identical in both males and females.
In females,the $23$rd pair consists of two identical $X$ chromosomes $(XX)$. In males,the $23$rd pair consists of one $X$ chromosome and one smaller $Y$ chromosome $(XY)$.
Females produce only one type of ovum. Each ovum contains $22$ autosomes and one $X$ sex chromosome.
In males,two types of sperms are produced. Half of the total sperms contain $22$ autosomes and one $X$ chromosome,while the other half contain $22$ autosomes and one $Y$ chromosome.
Whether the child will be a boy or a girl depends on the sperm that fertilizes the ovum.
Thus,it is clear that the sex of the child is determined by the genetic composition of the sperm. Furthermore,in every pregnancy,there is a $50\, \%$ probability of the child developing as either male or female.