I am 51 years old, my bio father paid for me to be born. Than released all rights. He to this day denies that he is my father.
I need proof, I have brothers and sisters that I want to meet, they will not meet me, unless I have proof. I have nothing, except the fact that my mother has told me his name and that he paid for me to be born, not in court it was done by a lawyer coming to my grandfathers home and giving a check and sigining papers. I have written him several letters, the first one when I was 26, I have sent them certified mail, where he has had to sign for them. He has never responded.
I really need proof, while he is still alive, he has to be in his late 70's or early 80's by now. Please help!

You are 51... You can't MAKE him get anything. Its clear he wants nothing to do with you. You have to respect his rights. I know its not what you want... but what he wants is just as important.

You've tried... you've done what you could... and unless he wants to see you or even respond to you... you can't force it on him. This is one of those times you just have to walk away, before he gets a restaining order. And he might if he is that resistant. He has his reasons... and they might just go with him to his grave.

Incidentally... being a sperm donor isn't being paid to have you born. Its being reimbursed for your time to help someone else have a kid that wants one and can't for whatever reason.

You are 51....You can't MAKE him get anything. ...

But, depending on his state of residence, you may have a claim to some share of his estate after he dies. At that point, I suppose, you could possibly seek DNA testing.

You can not force him and in fact if you harrass him too much he will get a restraining order from you.

His children are free to talk or not talk to you, Even if you are proven his son, most likely his other children will not want to talk to you.

If he is rich, you may try and make a claim to his estate at that time, and prove paternity though DNA of his sons.