If you don't restrict your sex life, there will be so many disasters.

Actually, we are seeking unlimited pleasure. Ananda-mayo 'bhyasat. How can this drop of water in the desert, which is materialistic pleasure, ever satisfy us? No one is satisfied, although people are having sex in so many different ways. And now young girls are almost going naked, and the female population is increasing everywhere. As soon as there is an increase in the female population, the women say, "Where are the men?" Then there must be disaster because every woman is trying to attract a man, and men will take advantage of this situation. When milk is available in the market, what is the use in keeping a cow?" The more men become attached to women, the more the female population will increase. When you have more sex, your power to beget a male child is diminished. When the male is less potent, a girl is born, and when a man is more potent, a boy is born. If a man's discharge is larger, there will be a male child. If the women's discharge is larger, there will be a female child. When women are easily available, men become weak, and they beget female children because they lose their power from overindulgence. Sometimes they even become impotent. If you don't restrict your sex life, there will be so many disasters.

Srila Prabhupada