In our society women are blamed for producing female children....

In human beings both females and males have the same number of chromosomes (23 pairs). Females are homogametic with XX chromosomes (22 pairs + $\mathrm{XX}$ ). They produce ova having $\mathrm{X}$ chromosome. All ova are similar. Males are heterogametic with $\mathrm{X}$ and Y-chromosomes (22 pairs $+\mathrm{XY})$. They produce two kinds of sperms, one type with X-chromosome and other with Y-chromosome. On fertilization, the zygotes may have either the $X X$ or $X Y$. The zygote with $\mathrm{XX}$ becomes the female and the zygote with $X Y$ becomes the male. The sex of the offspring depends on the fertilizing sperm.