Yes, you should provide this information in some form in your PS or elsewhere in the application. No, you shouldn't use it as a primary reason to explain your lower GPA. You will be expected to provide evidence (grades in advanced courses, MCAT, etc) that show you can handle medical school. However, your background, as it is relevant to your interest in med school and your life experiences, is appropriate to put in your PS.I come from a home of severe heroin drug abuse, throughout my childhood and up to the suicide of a parent I was exposed to drug trafficking, physical abuse, and was victim of physical abuse myself.
This came to an end when my parent committed suicide, which I found their body after coming home from school : (. I have worked as a bartender at night and at a dr's office to help with food, and bills at home. I have attended school full time and have a 3.2 GPA.
I want med schools to understand I am capable of handling vigorous coursework, but given my troubled home my GPA does not reflect that.