The breasts, which consist of both fat and breast tissue, rest on the foundation of the underlying muscles and skeleton. These foundation tissues may themselves be asymmetric.
Here are some causes of chest asymmetry:
There may be scoliosis (curvature) of the spine
There may be rib cage asymmetriesYour posture may be such that you naturally carry one shoulder lower than the other
One chest muscle may be larger than the other
One chest muscle may never have developed (Poland’s Syndrome)
The attachments of the chest muscle to the rib cage may differ for each side
There may be developmental abnormalities of the breast bone in which portions of it are caved in (pectus excavatum) or rarely just the opposite – jutting out (pectus carinatum)
Consult surgeon for examination and treatment...