Question

What is the probability of a girl or a boy being born into a family? Justify your answer.

Answer 1

There is a 50% chance that a girl may be born and a 50% chance that a boy may be born. It can be explained as follows:

• Most human chromosomes have a maternal copy and a paternal copy. We have 22 such chromosomes. One pair of chromosomes called sex chromosomes is odd in not always being a perfect pair. Women have a perfect pair of sex chromosomes, both called X. (XX)
• But men have a mismatched pair of sex chromosomes in which one is a normal-sized X chromosome while the other is a short one called a Y chromosome. (XY)
• A child receives one chromosome from the mother which is essentially the X chromosome.
• A child who inherits an X chromosome from her father will be a girl, and one who inherits a Y chromosome from him will be a boy.