what is the usual time to be “developed”? lack of any breast development by age thirteen merits some monitoring. the small firm breast buds usually appear about age eleven. by age thirteen a majority of girls have the beginnings of a mound-shape of breast tissue. unless there is an overt reason for lack of development such as illness radiation exposure or hormonal problems there is evidence that breast development can continue until one’s early 20’s. while most all of us have at least some difference in size between our two breasts there are situations where the size difference is very apparent. size differences which onset in teen years will likely equalize for about 75% of women. yours jane h-h
why is that my 10 year daughter is developing breast and only one of them is coming in? the other one is still flat?