Looking for answer (Long Post)

Amber

My boyfriend is 25 years old and believes he was adopted. He has asked his parents about this and they deny that he is. However he has never seen and pictures of him as a baby or pictures of his mother while pregnant. His mom also had open heart surgery at age 18 which would have been before she would have been pregnant but she would have gotten pregnant very shortly after. Which I’m sure is possible but sounds like it would be very risky to me. My boyfriend just would like to have a chance to find his real parents/family. He doesn’t want to shun the family he has now but just wants answer. I was wondering if anyone in this group has any advice on how to find out if he was actually adopted without his parents having to tell him?