The author's main purpose for describing her family is that despite facing challenges, her parents were kind and helpful.
Even though her parents never graduated from highschool, which makes advancing in a career or making a lot of money difficult, they were able to support all four of their children. They paid for their college education, including law school and medical school. This is a major financial feat. Even though the author mentions that growing up money was tight, she states that their parents were always warm and supportive. This is another way of saying they were kind and helpful.