I love this question!! It seems the Buddhists understood projection long ago.
Evolution has conditioned us with core strategies to preserve energy as a huge benefit to the odds of survival. And facing one’s baggage and emotional issues is incredibly destabilizing & exhausting. When your identity (sense of self) or worldview becomes disrupted, it’s almost the opposite of energy conservation. And your psyche is designed to do the opposite … preserve homeostasis … aka the “status quo”.
So parents unconsciously project their baggage onto the kids, and (semi-consciously) create the “identified patient” … the one in the family system with “problems”.
That’s the kid that gets sent to therapy while everyone else can pretend they are ok. This “identified patient” is a sacrificial lamb to the ongoing stability of the family system.
It’s totally unfair and fucked up, but unfortunately, the psychological physics and mechanics of homeostasis preservation make it an efficient (in the short term) strategy.
Parents can blindly but comfortably imagine that bad luck has befallen one of their kids, but “the rest of us are ok”, and we had NOTHING to do with creating the trap and many double-binds that this sacrificial lamb has fallen into.
How convenient and burden reducing for the parents!!
Dewey Gaedcke’s answer to What are the benefits of seeking therapy?