Identical twins one with BC the other w/I BC

I have an identical twin sister, but now we are not so identical. I was dx with stage 3A IDC/DCIS. It is interesting looking back at our histories and how our choices both voluntary and involuntary possibly led to me developing BC. So here goes the differences (please excuse the grammar).

First pregnancy with live birth: her 24, me 34. Both of us experienced 2 miscarriages.

Endometriosis: her none, me two surgeries and hormones.

Infertility: her nope, me 4 years with lots of surgery and hormone treatments.

Both breastfed our children: her about 1 1/2 years, me about 3 years total time.

Obesity: both not until after menopause.

Exercise: her not very much, me addicted to all things athletic.

HRT: her none, me 5-6 years.

Exposure to radiation via job: her none (R.D), me yes (RN oncology surgery).

Diet soda: her 40+ years of one liter/day, me one liter per year.

Family hx: yes, our mother dx stage one at age 70 and again at age 78. Still alive at age 93.5 years.

Smoking: not personally but 18 years of second hand smoke from our dad.

Alcohol: her minimal, me 3-4 glasses of wine per week x 15 years (I moved to wine country).

I look forward to hearing about other twins and their stories.

My sister and I are fraternal and diagnosed one year apart. Our mom has had two different kinds of breast cancer and is doing fine. We have been genetically tested and negative. Of course there is a link but is yet to be discovered. I don't worry too much about what caused the cancer because it doesn't matter any more. Even slender women who have children in their twenties and breastfeed can get it. My desire is to push past it and hope something is discovered in time to help our daughters.