I'll agree that people evince childishness regardless of age.

But I didn't say that "people evince childishness regardless of age".

I specifically said _jealousy_ is a trait attributed to humans as a flaw.

That has nothing to do with it being childishness or not. Otherwise it would be a trait somehow eliminated after childhood for a majority of adults, which it isn't since all of us (adults) experience it.

Furthermore, it elicits a sense of flight or flight, and causes a reaction, good or bad, I think. Again, it's a reaction; people in general aren't good at controlling those, nor do they last. A person can react as much as they want, but after a night's sleep, everything takes a different tone.

Our subconscious minds play a role that is probably undervalued. The jealous boss might wake up feeling relieved, invigorated.

Context also is important.

It's referred to as a "childish" flaw because in children the prefrontal cortex is not yet developed enough to mediate base emotional responses like that.

I don't disagree.

However, my point is that it is inherently a human trait/flaw, so adults experience it just as well.