samantha realized that she had learned this from her mother: there was a defensive way of living just like there was a defensive school of driving.
according to the teachings of the defensive school of driving, you were always on the lookout for possible collisions and accidents to avoid them.
according to the defensive way of living, you were always on the lookout for possible confrontations and friction to avoid them.
samantha's family never told her to live it that way, but acted as if she should follow their example. it was another incident of unwritten rules that were supposed to be followed no matter what.
while that attitude was all right for driving a car, she decided that it was a less-than-full way to live, and that would try another way.