To the specific point, I struggle to find any set of rules which is common across all cultures and generations; care to name a few?
Another is that parents' authority over children is sacred, as well as the bonds of marriage and friendship.
parents' authority over children is sacred
That's completely false, many societies (ours included) have imposed restrictions on how parents can raise their children, and sometimes in quite extreme ways (e.g. the Agoge[1]). And the child protection services in our modern Western societies take away plenty of children.
The rights of parents over children are more like the authority of the king in the Little Price - absolute, as long as they only use it in certain ways.
One can embrace nihilism without acting it out. We all have a choice to make: we can choose to follow the rules of our society or to not follow them. A small number of people choose to not follow them, and the rest of us choose how to deal with them to preserve the society the majority of us prefer. It happens every day.
It's all a choice, we have our free will that allows us to act however we choose. In the absence of absolute rules we can create our own rules to follow.
There is a set of universal standards and expectations have existed for millennia in many forms. There has always been an implicit set of common rules -- common across all cultures and generations -- that we as a species live by. Implying that everything is a social construction mental laziness and a desecration of our fore-bearers at best and malicious destruction of the bonds of society at worst.