Husband doesn't want to look anymore?

This might be in the wrong forum but I'm not sure where to put it. I'm not adopted. My husband is. When we first met he wasn't actively searching for his birthmom but he made it clear he eventually wanted to find her. A few years ago he and I got into an argument. I won't get into what was said but basically I was pretty insensative to his situation, although I didn't intend to be. I decided some time after that to do some searching for him. Every few months I would search a little, nothing would come of it and I'd wait a few months and start over again. Well, a few days ago I found two sets of people who were (are) looking for a son who seem to match up with his situation. Same birth month, state, city, etc. I only ever contacted the one (father) by e-mail. I sorta screened the guy before I mentioned it to Hubby. Everything the guy said about his situation seemed to match what my husband had been told. I decided to tell my husband that I might have located his father and mother. He was happy about it. Not overly excited, but happy. Needless to say, unless the agency lied to these people about who they gave their child to, my husband isn't their son. I told my husband I didn't think these were his parents but that I still have another set of people to contact who could be. He told me to forget it. He's not interested in finding them anymore. He says he's happy with his life and that is that. If I believed him I could probably let it go. He said before that he's afraid he will search only to find out she wants nothing to do with him. We did talk about it and he's agreed to request nonidentifying info along with giving his personal contact info in case she comes looking. Is it really possible that his birthmother would want absolutely nothing to do with him? Like he was some dirty little secret she wants to keep hidden from her new family? He was born in 1969 and I've heard about how sometimes women got sent away and were told never to talk about it afterwards. With all the time that has passed is it likely that she might still want it to be like it never happened? And what can I do to help him? I want to be as supportive as possible without pushing.