menachem – there is something wrong about your nusach, ‘based on halocha’. I think you mean that for Halachic purposes, or somethnig like that?
Either way, we rely on it even for when we don’t usually rely on rov, like אין הולכין בבמון אחר הרוב and also we can kill based on this, otherwise if you were mezane with your father’s ex wife or his sister, you could would still be killed. We
I think the achronim say that once it is paskened for other issues, we then use it for everything.
either way, the whole issue is only really halachic. Statistically the probabilty that you are a mamzer is almost 0, You rely on that sort of probabilty to fly airplanes without worrying you are going to die. so the whole shaila is only in Halacha, and in Halacha anyway we rely on the Rov, so really it’s quite theoretical.
For practical purposes you can check the DNA, nowadays many poskim trust DNA testing to a large extent. Ask your local OR. But even if you have proof that your father is indeed your father, you still can allow yourself the pleasure of speculating that you are a mamzer – maybe your grandmother was mezaneh, or one of your great great grandmothers….
coffee (and cheescake) addict: even though Menachem’s mother has a chezkas Kashrus, and she no doubt deserves her kesuba, it still does not mean that Menachem is not a Mamzer – maybe she was raped b’oines, in which case she would still qualify for kesuba but Menachem would be a mamzer if he was conceived from the rapist.