Reply To: Every Yids a safek mamzer

Given that being a mamzer is hereditary, so for most Yidden, that means assuming nothing that would make you a mamzer for well over 100 generations. We therefore have numerous presumptions that if someone seems kosher, and we have reason to believe it is kosher, it is kosher, so we can ignore the possibility that a Jewish ancestor of our’s over the last few thousands “cheated” secretly.