Very insightful, and very well said. I hadn't thought of it that way, but I think you have probably hit the nail on the head.

I should add though, that I think it works the other way too. You could also have the problem that the 35+ year engineers look down upon the 20 somethings and communicate it, perhaps unknowingly, in subtle, or not so subtle, ways.

It almost feels like an animal hierarchy problem where you have an older male being added to the herd and the young pack leader is worried about this older male challenging him, while the older male thinks he can and should challenge the younger one.

Makes me wonder then, do women face age discrimination?