Aunts, uncles, and cousins would likely be different, depending on the family. I have an aversion for many of these such family members, especially my cousins because they were raised so close to me, I saw them almost every day of my childhood, was loved and disciplined by my aunts and uncles, considered my cousins siblings (heck, I had one living with me for about 2 years, claiming her on my taxes, plus several have lived with my mother throughout their teens and twenties)(and I was there at the hospital when my older cousin had her son and her twins, we went to the same high school).
And you misunderstood what that line was saying about the aversion. It basically was talking about those siblings/relatives not raised with each other to pick up the cues. Plus, a person doesn't have to have a malfunctioning brain result from abuse. It can simply be manipulation to prevent the aversion from taking hold, even if the person doesn't know anything about the actual aversion.