answer is, it is our mother who has seen our father before our birth and knows it that who has tilled her. So you have to ask from mother, "Who is my father?" And if she says, "This gentleman is your father," then it is all right. It is easy.
Otherwise, if you makes research, "Who is my father?" go on searching for life; you'll never find your father.
similarly we have to listen to the recognized agent of Lord Krishna such as Srila Prabhupada. this is the process. here is the name of that God, Krishna The Supreme Personality of Godhead.