These small breasts with stretch marks have fed seven children - and the youngest one continues to nurse at four years old. Below you can see close-up photos of the left and right breast to see the stretch marks better.
Here's another picture of stretch marks on a breast:
The tendency to get stretch marks depends on the elasticity of the skin, and is largely hereditary. Diet plays a role, too. Stretch marks can appear when the skin is forced to stretch a lot in a short period of time, like during pregnancy, during quick weight gain, or during a very quick growth in puberty. Usage of anabolic steroids, or even some common drugs, for example hydrocortisone or steroid creams, can result in stretch marks. Once you get them, they don't go away but they do fade a lot over time and can become practically invisible in untanned skin.
There are also various creams for stretch marks available but most of the time they have not been proven to work. People usually spend their money in vain. Searching for reliable information about stretch mark creams is very difficult.
Though I cannot guarantee they will work, you can check the webpage Stretch Marks from Dr. Emily kane for lots of ideas on how to prevent stretch marks.