Most scions of prominent lines start going off the rails by III, highly likely to be homosexual by IV and the very few V’s who manage to sneak through that gauntlet of instability and disinterested parenting all wrapped up in deviance are as nutty as a fruitcake. The old “shirtsleeves to shirtsleeves in three generations” became a truism for a reason.
It certainly appears to be the case, and it makes sense as well. The lap of luxury tends to soften after many generations.