Respect your father's wishes and leave it alone.
Whatever your father's reasons for not wanting to find him, their relationship is between them and you shouldn't get in the middle. I doubt if he's looking for your dad. Have you ever realized that there are biological parents who don't want to be found? I had a good friend once who finally found her biological father, His only words to her (she was 55 at the time) were "I didn't want you when you were born and I don't want you now." He then hung up the phone and the next day he had an unlisted number. What if you found your grandfather and he responded to you that way? What if he's in jail for murder? What if he's in a mental institution for life? What if he's a ********* in prison on child *********** charges? There are reasons not to go looking for someone who perhaps doesn't want to be found.
And what if your best friend is your cousin? Would that mean you have to stop being friends?
Just leave it alone.
It's something for your father to know, you could though, but if your father don't wanna know, respect his wish. Talk to him if you wish to know him
None of your business. If tyou care that much about the man, have a little reserve and modesty for the wishes of your elders for **** sake.