Richa will try to convince her family by explaining them about the phenomenon of sex determination in human beings in which male possesses one X and one Y chromosome while, a female has two XX-chromosomes. If an ovum fertilises with a sperm carrying X-chromosome, the zygote develops into a female (XX) while, if an ovum fertilises with sperm carrying Y-chromosome, the zygote develops into a male (XY).Hence, it shows that the genetic make up of sperm, which fertilises the ovum determines the sex of a child. Thus, it is not right to blame a mother for the birth of a girl child as it is a by chance phenomenon because there are both 50-50% chances of having either a male or a female child each time a female becomes pregnant.