Yes, you read that right. I did write all children are psychopaths.
What proof do I have? None whatsoever.
But remember that time you had to teach your little precious that other people feel pain too? That other people can feel sad? You know why? Yep, it's because your little precious is a psychopath.
Now don't get me wrong — he or she or it is probably be a cute little psychopath. They kind of have to be to survive past the age of five.
By the time they're teen-aged the cuteness wears off because they don't need it any more. By now you've probably become too attached, invested too much into your psychopath to do anything about it. Hence the so-called "terrible teen years". Don't delude yourselves: they've always been terrible. They just stopped being cute.
There's not much you can do about it now (legally) other than persevere and hope your psychopath develops into a proper human.