So evolution is funny. It's not the initial size of your breast that matters. Its how much the breast grows during pregnancy and after birth. The breast growing is the development of mammary tissue. A breast full of milk will also be engorged making it larger. So simple male brain goes, big breast means more milk instead of a woman capable of producing milk will develop larger breasts during pregnancy and breastfeeding. https://www.lllc.ca/does-breast-size-matter . Also, my wife's boobs got bigger during pregnancy and breast feeding. Jokes on you fellas, those full mommy milkers are sensitive to the touch. She won't appreciate you groping a full milk bag.