The female breasts exist to give milk to their babies. Since many men prefer women with big breasts, instead of small ones, many women try to increase the size of their breasts (within reason) to appeal to men. Most men do not like breasts that are too big.
We can grow big breasts by doing sex with other boys because they suck our breasts.
BIG
Girls develop breasts so when they have a baby, they are able to breastfeed. During pregnancy the breasts get larger and fill with milk to feed the baby. Those are the main reasons girls develop breasts.
as big as God intends
Big.
As Big as E
Big breasts are 'des gros seins' (familiar/slangish) in French.
Genetics.
It varies!
A cup
I guess that depends on how big your breasts are....?