Reply To: what’s the yichus of yichus?

the gemara says that everything a child has comes from either his father or mosher – end of sukah. see also tanya last page of chapter 2, that explains that the livush of the child depends on the holyness of the parents when the child was conceived, but the level of neshama not necessarily. see also raoshis chochma shaar hakdush.
see also sh”u that a child from parents who did not keep taharas hamishpacha can have a pgam in his middos, also the gemara says that if when the child was conceived the parents did not have shalom bayis, destracted by other people, drunk that can effect the middos of a child.
very important who the parents are, but children can always do teshuvah or the opposite. chitas and osios hatorah has a great effect of the neshama even if there is issues with the yichus.