Now we will discuss whether the father or mother is responsible for the birth of a son or daughter. Both male and female have 44 autosomes, A and a pair of sex chromosome. Sex chromosome of a female is XX and that of the male is XY. The male gamete (sperm) bears X and Y chromosome. But the female gamete (egg) bears X and X. If the X bearing egg of the female is united (fertilize) with Y bearing sperm of the male, the child will have XY.
A child having such chromosomes will be a male child. It is seen that if there is no Y chromosome, the child will never be a son. There is no Y chromosome in a female; Y chromosome is present only in male. So if a couple do not have any male child, the husband is responsible not the wife. A figure on this issue.
The role of sex chromosome in determining sex of the child (i.e. whether the child will be a son or a daughter) is known to you. Now work with this grid. Write which child will be a son and which one a daughter.