Depends on the age. Girls from the age 0-11 usually don't have boobs. Girls from 12-14 have A's, 15 usually B's.. But, everyone older varies. C's are normal size, D's are big, Double D's are huge.
Most guys do.
We can grow big breasts by doing sex with other boys because they suck our breasts.
That is generally true that you may get the attention of most of the boys, if you have bigger breasts. But then, you are getting the attention of the boys as a sex objects. You are not a sex object. You should get the attention of the boys as a person. Big breasts are not necessary for the same.
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.
BIG
as big as God intends
Big.
As Big as E
Big breasts are 'des gros seins' (familiar/slangish) in French.
Different people have different perceptions of what is considered big breasts. Some might consider a C cup big, but most would consider a D cup to be be big breasts.
I guess that depends on how big your breasts are....?
Genetics.