Breast size is hereditary. You have an equal chance of inheriting your chest size from either parent, which is why your sister may have much.
Smoking can cause breasts to droop, but breastfeeding doesn't.
Ditch the pink this October and spread breast-cancer awareness with these 31 facts about breasts. In most women, the left breast is usually slightly larger than the right. A slight difference in size — up to 20 percent — between the right and left breast is normal.
Big or small. Perfectly round and perky, or asymmetric and quirky. Every lady's lady-lumps - and I'm talking about breasts, in case it wasn't clear.