Hello all, this is my first post here, and the doubt that led me to this forum.

If I got the concepts right, the key point about paternity tests is that Y chromosome passess without modifications, so I guess there will be very little difference on testing with any paternal line ancestor. I've made a picture to ilustrate (on the left, maternal line, right paternal), 'A' is the actual father relation maybe he gets 99.999% on the test, '1', '2' and '3' will get the same 'probability'? Or a little lower...

One of the specific questions I have, is if a male from maternal line shows any impact on the test, for example, will the brother of the mother of the father, ('5') show a greater result than a complete stranger to the family ('6') when tested for paternity?

i.imgur.com/9xs0hZz.png <- Picture as is not letting me to embed links (posts < 10), add 'https://'.

The other question that arises to me if paternity tests results are expressed in probability of being the father, and the response to me is a sound no, for the probability of a certain fact is 1, and if testing 2 independent events p(A):Father is the father = ~.9999, p(B):Father of the father is the father = ~.9995 the answer is we are not talking about probability.

Thank you in advance for your insights.