Hi Alex.
I agree with the previous posts. Though the lumps in both breasts can be a result of hormonal changes in her body, she should have it checked. It is not common for an 18 year old female to develop breast cancer. However, a strong family history of breast cancer places one at an increased risk. There is such a thing as hereditary breast cancer.
Regards
Hi Alex ... with her family history she really should see her family Dr. for a clinical breast exam. More than likely considering her age these lumps are benign in nature but NOTHING new should ever be ignored. Her Dr. may very well order a Mammogram to have as a baseline or maybe not if he/she is certain after examination that the lumps are related to hormonal changes in the body. This is a common occurance in women of such a young age. Regards..
At her age, it is probably fibroadenoma, but with her family history, she should have it checked anyway.
"women on her mothers side had it"****** (edit)