mazbook1, I like your addition: It takes two to do the dance. and Yes, I agree that I am projecting a NOB perspective on "blaming the parent" that may not fit here.
I still like the "Mom - itis " . I can't shake the image of a little boy, grasping at and hiding in his momma's skirt = en las faldas de mamá. The joking about mamitis I hear here are directed at adult men, who just can´t let go.
For those of you with cuñados, you now have an new way to zing him. *grin*