How a DNA test proves that i am biologically related to a man?

Question

Assume i take a DNA test to know between two men which one is my father and which one is my father's cousin(their fathers are brothers), how do they gonna test it in these two different situations:

A) a test with no sample of my father

B) a test with sample of my father

in both situation a sample of the mother is available.

i am talking about the X-test, Y-test and MT-test(mitochondry test). how do they gonna compare these things?

this is ergent. its my biology test.please help!

thank you.

Answer 1

Don't take the MT-test. Mitochondria are passed down only through the mother. So both of these men would have different result than you even if they were your father because you do not share the same mother.