How to paraphrase the underlined part in the following passage? Thanks.

Parents should stop blaming themselves because there's not a lot they can do about it. I mean the teenager problem. Whatever you do or however you choose to deal with, at certain times a wonderful, reasonable and helpful child will turn into a terrible animal.

I've seen friends deal with it in all kinds of different ways. One strict mother insisted that her son, right from a child, should stand up whenever anyone entered the room, open doors and shake hands like a gentleman. I was him last week when I called round. Sprawling himself on the sofa in full length, he made no attempt to turn off the loud TV he was watching as I walked in, and his greeting was no more than a quick glance at me. His mother was ashamed. "I don't know what to do with him these days," she said. "He's forgotten all the manners we taught him."

He hasn't forgotten them. He's just decided that he's not going to use them. She confessed that she would like to come up behind him and throw him down from the sofa onto the floor.

Another good friend of mine let her two daughters climb all over the furniture, reach across the table, stare at me and say, "I don't like your dress; it's ugly."One of the daughters has recently been driven out of school. The other has left home.

"Where did we go wrong?"her parents are now very sad. Probably nowhere much. At least, no more than the rest of that unfortunate race, parents.
Where did we go wrong? is an idiomatic use of the word "where." It means "What did we do wrong?" so there is no actual place. This writer is using a little play on words when he says "nowhere."

Here is the paraphrase: You probably didn't make any real mistakes in raising your children. If you did, you didn't make any mistakes that aren't common to most parents, who are all in the unfortunate position of having ill-mannered teenagers.
QingqingProbably nowhere much. At least, no more than the rest of that unfortunate race, parents.

Hello Qingqing,

My take:
Probably, just like the other parents, we didn't do anything wrong (did no wrong).

All the best,
Hoa Thai