Nobody said anything about rounding up anyone for their ancestor's misdeeds. Where did THAT come from?
Any culture today that sentences rape for a teen girl as punishment for her brother should be eliminated from the planet, as pure evil. Do you agree? Yes or no?
Any such culture needs some serious work, I would agree. Not sure I'd go so far as to suggest wiping out all the members of that particular culture, though.
Cultures, or aspects of a culture, can be destroyed without wiping out the people unfortunate enough to be born into them.
No. And your question is based upon a false assumption.
The culture didn't sentence that girl to be raped, a few corrupt, evil judges and townspeople did. If rape-as-punishment were the usual penalty within a culture, don't you think that we would be reading about incidents like this every day?