How is this book a tale of survival?

Jeanette's parents belief in self sufficiency has a great deal to do with the family's survival.

"Even during their hardest times, Rex and Rose Mary Walls refuse to become charity cases. They do not even accept help from their children in their late adulthood. The value of being self sufficient descends mainly from Rose Mary Walls, whose upbringing in an incredibly disciplined home leads her to forgo the rules when she becomes a mother. Her children, she insists, must learn how to be self sufficient and strong. They should not rely on society or doctors or anything else to help them through life. Even when they fall ill or injure themselves, Rose Mary prefers to treat the wound at home rather than cater to what she considers a false need to visit the hospital. Though the Walls value self sufficiency they are not always able to maintain it, and sometimes their methods are not sufficient for survival at all."