Explain how sex is determined in unborn babies.

Hint: The sex of the unborn child can be genetically ascertained by determining the type of the male chromosome that gets fertilized with the female chromosome.

Complete answer:
Humans show the XY pattern of inheritance during fertilization.
-Every human being consists of 23 pairs of chromosomes. Out of these 23 pairs, 22 pairs of the chromosome are exactly the same in both males and females. Therefore, these 22 pairs of chromosomes are called autosomes.
-However, the 23rd pair of chromosomes between the males as well as females are different. They are called sex chromosomes.
-The sex chromosome for the women will have a pair of X chromosomes. On the contrary, males will have a single X and single Y chromosome.
-During sperm production as well as development(spermatogenesis), males will produce one X and a Y chromosome. In other words, 50 percent of the entire sperm production will yield X chromosome and 50 percent of the will yield Y chromosome.
-Females will produce only X chromosomes.
-During the process of fertilization, the ovum can fertilize with sperm containing either of X or Y chromosome.
-If the ovum fertilized with the X chromosome, then it results in a female baby (XX) whereas, if the ovum fertilized with the Y chromosome, then the baby formed will be a boy (XY).
The above image represents the female and male offspring formation.


Note: All the chromosomes in our body are 2n (diploid). But, ovum and sperm (gametes) or the sex chromosomes are haploid in nature. So, once fertilization occurs, the haploid ovum and haploid sperm will fuse to form a diploid zygote.