I agree.
It is an error to attach some adventitious value to biological relationships. The word “father” for example, tells us nothing about a given man except that he has reproduced. A more useful term for that is male progenitor, with "father" reserved as a designation to be applied when certain other conditions are met, such as a commitment to care and protection, the parental attitude, a moral and emotional orientation. And in that case, of course, the biological link is unimportant.
To plead, "But he's your father!" or, "You only have one father!" is biological essentialism and means absolutely nothing since the same can be said for crocodile hatchlings and lion cubs whose "father" devours them to expedite the estrous cycle of his mate and fast-track his next opportunity to copulate.