Ancestry identified my birth father’s family for me. Since I was born in 1945, when everything was kept hush, hush, the only one still living wouldn’t even give me her real name, much less any medical information, which was mostly what I wanted.
Whatever you decide to do, please, please be kind. There is a belief that adoption mends the primal wound of being given away by a parent. It isn’t true. Even happy adoptions do not mend that wound. Finding the birth family doesn’t necessarily heal it either. You may find you are now dealing with a very jealous, sharp tongued sibling you could have lived without.
Oh yeah, we connected and made him feel at home I believe. He was able to meet his biological full brother. Unfortunately his mom and dad had passed away some years ago. It’s a similar situation to you- he was born in ‘55 to my great Aunt and Uncle who had him before they got married. Their other children had no idea they had an earlier child given up to adoption.