At some point a person's parents have a very tenuous influence on their children's behavior, even if the parents were way better than average at rearing their kid.
From a legal perspective, in many states a person having attained the age of 18 years is considered an 'adult' and is fully responsible for their actions - independent of how they were raised.
And of course, the process of 'natural selection' is such that how a person was raised by their parents doesn't factor at all, and sometimes catches those many think have superior intelligence.
So very true. I thought I taught my kid how to safely cross a street. Cross at the corner, stay within the crosswalk lines, be aware of cars not following the rules (like exercising their right to turn on a red, and when doing so, never actually looking to their right to see if their direction of travel is clear), wait for the "walk" sign, and so on.
A year ago, took him on his college visit, which was in the big city. While we needed to cross a busy city street, he steps right off the curb! I grabbed him and pulled him back. At 18, he got a long, long lecture reminding him of the rules of crossing a street, especially if he wanted to go to a college with a split-campus located in the middle of a big city.