I think you need to turn these hard questions over to professionals in the field. Lay people all have opinions, but they DON'T know how to handle it, and all kids need a different type of handling anyways. Kids with a driving need to know their roots (heck, I would have been one of those kids--I have unrelenting curiousity) in my opinion do need special help and understanding to become whole and productive people. Here is what's going on with me and my precious youngest (she is my favorite child, although you are not supposed to have a favorite. We are mother/child, best friends, soulmates and have absolute trust in one another. And she is curious about where she came from.
I've been in contact with adoption therapists constantly these past few months. Many adopted kids DO care about the birthfathers AFTER they find out "why" from the birthmothers. Our stories aren't good enough; they want to hear from the horse's mouth why they were given up. Were they defective?Were they bad? WHY? And only the birthmother can tell them, if she is willing. I have four adopted kids my girls were the ones who were the most interested. The birthmother carried them for nine months and she is #1 on their list. After that, the birthfather becomes a curiousity to many kids.
I strongly recommend adoption counseling for the kids before any contact is made and if your boy is upset by his adoption (this is common and has NOTHING to do with his attachment or love for you) I'd take him to a counselor who specializes in adoption issues. He can work through his fantasies or feelings of abandonment or not being "good enough" that we, as their adoptive mothers, can't change. I also highly recommend the book called "The 20 Things Adopted Kids Wish Their Parents Knew" by Sherri Eldridge. I have a great relationship with my youngest and we can talk about anything. When I asked her stuff from the book, she shocked me by agreeing wtih all of it. Of course, all kids are different, but I think it's a very informative read.
I also think adoption counseling by somebody who really understands adopted kids, and their special issues, is great. It has made us a closer adoptive family, more ready to man the ship with our daughter's adoption questions. It also gave me an outlet to cry and express my own silly insecurities and then lift my chin and boldly face my daughter like a mom in control (yay, right!). Your son will probably feel a lot better with somebody to talk to who actually understands what adopted kids (some, at least) deal with. It is NOT the same as being born into a birthfamily because there are so many abandonment and identity issues. If the child is of another race like ours, that is another issue. In general, I have a grounded, well adjusted twelve year old girl, but she has questions about her past and love for her birthmother and she needs to be able to talk to somebody who can validate her feelings and help all of us as we try to reconnect with the birth relatives of hers who are willing to see her--but my daughter AND these birth relatives also need to respect reasonable boundaries. Anyway, you just struck a note with me since I'm going through this now with my precious child. I hope I helped and didn't just ramble on...lol. Adopted kids get such a bad rap on televison, in the media, etc. They are seen as living in a "second best" situation...often they do need counseling to grow strong and proud, and they need to learn how to answer other's obnoxious questions such as other kids asking, "Where are your REAL parents?" "WHy did they give you up?" "Oh, it's so sad that you are adopted." My daughter hears this. My sons who are adopted heard this and got the message loud and clear. My oldest daughter heard this and still does, but she's sassy and has good comebacks, but it took her years (and drugs) to find hserlf. She is considering searching for her Korean birthmother. I gave her all the phone numbers and info she needs. It's just a matter of time and she has our blessing to search. She will always be connected to us, but our adopted kids have other families too--the ones who gave them their hair and musical talent and genes. It is natural to want to see somebody who looks like us.