We’re all born with mammary glands – better known as breasts. These are made of glandular tissue, fat and the ligaments that attach them to our chest wall.
For roughly half of us – those born biologically female – our breasts will change dramatically in size and shape at puberty. Size is largely genetic: genes explain 56% of the differences in breast size between people. But breasts may also change during pregnancy and breastfeeding, and can be affected by age, diet and exercise.
