I didnt read the whole thread but IMHO yichus is 00000! In today’s day and age, roshei yeshiva and gedolim can raise the most rotten of rotten children. I’ve seen this personally! Kids who’ve gone OTD and totally rebell and kids with awful middos. Yes, any parent can raise such kids but I’m saying the fact that their gr8 grandfather duzn’t mean a thing. Children aren’t products of their home anymore. Besides there’s yeridas hadoros.