From What Depends Breast Form

Chest - this is the part of the female body, which is given increased attention. Beautiful elastic breasts are the dream of any woman. But not everyone gets from nature a perfect breast, because the shape of the breast depends on the genetic characteristics.
The appearance of the breast largely depends on how it is located in relation to the chest (more precisely, from the surface of the abutment to the chest), the density of the tissues, size, shape. All these features are inherited by the woman. The shape of the breast depends on the size and pattern of the sucking mug, which can be round, oval or not, and from the shape of the nipple, which is conical, oval, round or shapeless.
Very often asymmetry of the left and right mammary gland occurs. If it is strongly expressed, then this is considered a cosmetic defect and requires correction. Correction of breast asymmetry is performed with the help of a plastic surgery called "mammoplasty".

It should be noted that the shape of the breast and even its size do not remain the same throughout the life of a woman. Breast changes, and more than once. This happens under the influence of various factors. For example, the condition of the mammary glands is heavily influenced by weight changes. So, after a sharp weight loss and reduce the amount of fat in the body, the breast can significantly change its size.
The shape of the breast also depends on the level of female hormones that varies during different periods of a woman's life: during the menstrual cycle, pregnancy and lactation, and during the menopause.
The shape of the breast changes after breastfeeding. Many women note that the breast decreases in size, loses elasticity, hangs. This is due to the stretching of breast tissue in the process of feeding.
The process of lowering the breast (in the medical language it is called "ptosis") is associated with age-related changes: with a weakening of the muscle tissue that supports the mammary glands and a decrease in the elasticity and elasticity of the tissues of the mammary gland itself.

To maintain the chest in good condition, you need to perform a special exercise (the most effective is push-up from the floor). With significant changes in the shape of the breast, when physical education does not help, they resort to plastic surgery. With the help of plastic surgery, you can not only improve the shape of the breast, but also change its size: increase or decrease.