Explain why in humans, the probability of a newborn baby being a boy is 50% and newborn baby being a girl is 50% with the help of the mechanism of sex determination in human beings.

Humans inherit their parents' genes, which determine whether they will be male or female. The sex chromosomes are perfectly matched in females (XX). However, men have an unbalanced pair of chromosomes (XY). Regardless of whether they are boys or girls, all children receive an X chromosome from their mother. As a result, the children's sex will depend on what they inherit from their fathers. A girl will be born if her father gave her an X chromosome, and a boy will be born if he gave her a Y chromosome.

Hence, in humans, there is a 50 % probability of the birth of a boy and a 50 %probability that girls will be born.