I can certainly understand your husband's feelings. He's been there for the boy for years while Bio-dad has been off doing whatever it is that people do that's so much more important than raising the child they helped create or being a husband to the woman who carried and gave birth to that child.
Unfortunately, it's not his decision to make. You can't prevent your son from seeing his biological father, regardless of the guy's piss-poor performance in that role thus far. Even the worst bio-parents have rights, and if you tried to block him from seeing the kid, I'm almost certain he could take you to court and win. Not that he would, but he could.
More importantly, it wouldn't be fair to your son. If he wants to hang out with his dad, and doing so doesn't put him in danger, then it would be wrong of you or your husband to try to stop him. If you did, your son might hold it against you for the rest of his life. No, the kind of relationship they are meant to have isn't your decision, or your husband's, or even the biological father's. The decision is your son's to make.
At 12 or older, your boy is mature enough to decide for himself if he wants to hang out with his biological father, and chances are he does, even though the man has been MIA his entire life. Not only is he curious, but children naturally want to be close to their parents, and they often create an idolized image of an absent mother or father to help explain and justify their absence. Now that Bio-dud is back in town, it's normal for your son to want to see him.
If he does, and they start getting together regularly, I think that sooner or later the honeymoon phase with Dad will wear off, and your son will have questions--you know, stuff like, "Where the f**k have you been for the last 12 years?" It won't take long for him to see that his father is nothing like the man he romanticized in his mind, but more like a guy who ran out on his family--unlike your husband, who has been there for you and your son all along.
Of course, there's always a chance they will hit it off. Maybe Bio-Pop has changed his ways and embraced responsibility; maybe he's ready to be the dad he never was. If that happens, good for your son--his dad is back in his life, and Stepdad will have to accept it. It's not a contest--there's room for both men in your son's life.
Whatever the outcome, it's not your place to interfere if your son wants time with his biological father. You just have to let this one play out.
"Bio-dud" HA! Great word! That might be one for the dictionary. I love the Jupiter tag too.
I agree with Cary's answer but I think you should mention to your husband that he could adopt your son, that way lawfully he's looked upon as the father and it'll also probably reassure him.
Great point.
I am going through the same thing right now. My son will be 5 in March. His bio dad was just tracked down through the courts. I have an amazing fiance in my life who loves my son just as his own. His bio dad has only saw him 4 times his whole life. I want him to be a part of our sons life. It kills me to see him with his other son and not acknowledge my son. I am so torn right now because of this. I want him to be a part of his sons life but at the same time my fiance says he doesnt want him in his life cause he is his dad in all respects that matter, and to an extent he is correct. But I cant bring myself to tell his bio dad that he cant have any contact with him. I would never do that. I just wish that this wasnt as hard as it is...
Wow, My husband wants me to send my son to his dad who just showed up or he will leave me?? So seems like all of us are in big time trouble.