To: My dad was adopted at 2 and he took on his adoptive parents’ British surname.
Me: You just don’t know. You can speculate, but that does not mean that it will be so.
Your father was put out for adoption or abandoned by his birth mother and adopted by his adoptive parents and he owed the life he enjoyed and the person he married for you to be born and have the life which you now enjoy.
I doubt his real parents wanted him, so why do you think they would have wanted you either?