Men have two kinds of sperm, X and Y, while women have only X eggs.
If x sperm and x egg combine and become xx, it is a girl;
If y sperm and x egg combine to become xy, it is a boy.
Generally speaking, both X sperm and Y sperm are randomly combined with X eggs, but a woman's physique will determine whether to have a boy or a girl.
Human constitution can be divided into acidic constitution and alkaline constitution. If women are acidic, X sperm can easily combine with eggs and give birth to girls.
If women are alkaline, Y sperm is easy to combine with eggs, and it is easy to give birth to boys.
You got it? Whether to have a boy or a girl depends on your physical fitness. Different constitutions mean different chances of having boys or girls.
You can consult your doctor about your physical condition.