@Saverage Theres also Long Lost Family US which is quite good, and I think is on Quest or More 4, or one of those channels. They do it slightly differently, but still fascinating.
We discovered my uncle was adopted after my grandparents died. My mother, his sister, never knew until then. Lots of unanswered questions, as my gran had children naturally afterwards. We’re not sure whether he ever knew. He never let on if he did.