I was flat chested until I was nearly 19, so it may be just a coincidence and not the Iodine. On the other hand, the Iodine is giving your body what it needs to produce hormones efficiently. So if your breasts are growing, they are probably just fulfilling their potential, so to speak. Are they bigger than you would like for them to be? My breasts seemed to get a little smaller on the Iodine, but I was in my 40's when I commenced with it.