From what I've learned, as it happens, nuns are, as a demographic, at a higher risk. Risk factors (amongst others) are...early menarche (first period), no pregnancies, no or little breastfeeding, overweight, alcohol and more. There is also recent and ongoing research into breast cancer in transgender (male to female) people. Seems to me that the hormones play a large role. The pregnancies and extended breastfeeding change things. I know that for me, I had one period between conceiving my son, breastfeeding him for two years and four months, conceiving my daughter (there was the one period inbetween), and then feeding her for two years and one month. I started my periods at age fourteen, had three babies (lost one), fed two for extended periods of time, had no family history at all, was not overweight, very occasional social drinker, and so statistically, should have been low risk. Tell that to the Cosmic Clowns.
