Human breast milk contains all the nutrients a human body needs.
A human female can create an infinite supply of breast milk but will lose 10 IQ point for every ounce of milk drank till they reach an IQ of 40
A woman can drink her own milk with no downsides.
Oftentimes the youngest male of a family will be given full legal control over their female family members unless they are found to be abusive to the family.
At the age of 25 a woman may choose to go out on her own. Their father is still expected to pay for them but they no longer have to give access to their breast milk to anyone other than that youngest brother if they have one.