What does being put in cheirem mean for you and your descendants?

Question

A (not-so-observant) friend of mine recently told me that his great-grandfather was put into cheirem and, not being able to have children while in cheirem, his descendants (including my friend) are unable to marry halachically. I’d never heard of anything like that but, unable to find a comprehensive explanation on what exactly cheirem entails, I thought I’d ask a few related questions that come to mind:

Does the fact that a Jewish court put someone in cheirem mean that they are universally see as being in cheirem, separated from the entire Jewish people, or is it only that particular community that they are restricted from certain interactions with?

Can you really not have children in cheirem?

Is cheirem something that your descendants are stuck with forever, or does it only apply to the person it was placed on originally?

Answer 1

What you're describing sounds more like mamzerus than cherem, one should investigate this with an Orthodox Rabbi rather than here, as mamzerus is a serious issue that needs to be dealt with properly. Otherwise, I've never heard of someone in cherem alone who was prevented from having children. Rarely does cherem extend outside of a local community, and it regulates ones social relationship between fellow Jews and oneself, not one's decendents, or marriage.

Answer 2

The gemara in Moed Katan 15b explicitely writes one can have relations and children while excommunicated

What is the halakha concerning one who is ostracized with regard to sexual relations? Rav Yosef said: Come and hear that which is taught in a baraita: All those years that the Jewish people were in the wilderness they were ostracized, and yet they engaged in sexual relations, as there were children born to them during that period. It follows that it is permitted for one who is ostracized to engage in sexual relations.

In any case the excommunication stops with the death of the person and is not inherited by the person's children (Moed Katan 15a speaks of the death of an excommunicated and doesn't mention anything for his children - nor do the halakhic codes).

As suggested by this other answer, it is possible your friend was speaking of something else.