Should I Contact the Adoptive Parents?

I would say absolutely try and contact your sons parents. There's no guarantee what reaction they may have, but I would say for your sons sake (for medical history as well as a potential relationship) you should definitely try. I think it's wise to keep an open mind because everyone reacts to contact differently and most of the time it seems to take time to build trust. Just be honest and upfront with why your making contact and then the ball is in their court. I hope things turn out well for you. Also, you may want to post this in the General Adoptive Parent board. It gets the most traffic.