As we all know breast milk is full of goods. It changes depending on the age and needs of a baby. In humans and other mammals, researchers have found that milk composition changes depending on the infant's gender.
More recently we’ve learned that mothers produce breast milk with significant variations in nutrient content for boy and girl babies.
Researchers at Michigan State University for example found that among 72 mothers in rural Kenya, women with sons generally gave richer milk. Another study showed also differences between the genders in the contents of their mother’s milk. While carbohydrate content was nearly identical in both sample types, it was shown that boy babies receive higher levels of lipids (fats) and calcium than girl babies.
Researchers are still not quite sure why it happens but one assumption is that males have higher muscular content than females, they require more fat and protein. Heavier bones in males require more calcium during development.