Usually women experience the heaviest breast growth during the adolescent teen period of ages 12-20, sometimes starting a little earlier and ending a little later, depending on the individual .

My little theory on why girls start puberty and start growing “big breasts” so much earlier now is the abundance of synthetic hormones and hormone-mimicking preservatives and substances that have overtaken our food supply now, but that’s beside the point.

The thing that primarily determines your breast size, which can always of course be an exception in any woman’s case, is heredity and genetics, which are actually just about the same thing, except genetics determine a lot more in your body.

Heredity strictly refers to the fact that you “inherited” certain traits directly from a familial descendant of some sort, most often a female descendant of close relation, like your mother or grandmother.

Although, some of you are thinking, then why does my grandma have big bazookas and I got size A’s? Like I said, it’s not a 100% positive thing with everyone, but it is a fairly safe bet that if you come from a long line of very thin women with small breasts, you will probably end up the same way, or vice versa.