Hello. I hope this helps.
Abuse
There also are several research studies that have been done on children who were abused, revealing that, as adults, children who were hit developed psychological and relationship problems.
I knew being hit was wrong because I saw criminal T.V. shows and movies where parents and other adults were summoned in court and being sent to jail for hitting their children. Also, I knew that my friends' parents didn't physically abuse them, nor their spouse, when they did (and even when they didn't) do anything wrong. Mine were either grounded or sent to their room. My kind teachers, who didn't abuse any of my classmates, also helped me, by their example, that it wasn't normal for other adults to treat their children like that.
Also, another clue that it's wrong is, notice that abusive relatives demand their children to be perfectly behaved, without expressing emotion, like an adult (when that's not developmentally possible for children because their brains aren't developed, yet, because they're not adults), yet think it's okay that they can hit others, fly off the handle, and shout at them, acting like children themselves?
Just like the Nassar abuse survivors who tried to tell their parents and police that they were being abused, I wasn't believed, either, when I tried speaking up as a teen. I felt so hurt and ignored that adults around me, even the police, were telling me I deserved it, because they were hit, too, as children; I felt suicidal, afterward, and had to comfort myself into not doing it, telling myself that doing that would only be what my parents wanted (since my mother told me I should do it, several times), and that I knew I didn't deserve to be blamed for their marital problems.