My wife went through a similar thing. Her adopted parents knew about it and were OK with it. I think she started with a judge to unseal the records because she was having a medical problem and wanted to find out actual family history. Even at that, certain information was hidden. But she did find out she had 2 older brothers and an older sister and some basic information about them and known medical history. I think the medical history search was the thing that clinched it for the judge. I don't remember if she eventually got a name or accidentally saw something she shouldn't when she got the records she did, but we eventually tracked them down.
By the way, most birth certificates are changed to show the adopted parents, so that doesn't help.
Her mother died 20 years ago. She has a half sister who she's met, and two half-brothers who she hasn't. As far as we can tell, her mother was divorced and had an affair that produced her. We have no idea who her father is (judging by our daughter, I'd say he was probably a circus acrobat). The siblings were sent to live with grandma for a few months, so they didn't even know they had a sister.
I thought finding them was great. From the moment I saw my wife's adopted family, I saw she looked out of place. She looked different and behaved a little differently. When she told me she was adopted, I knew why. I think you get to know a person better by seeing their birth family. Some things she inherited from her birth family, not from her adopted one. Meeting her sister let me get to know my wife better. It also gives me insight into our children.
But, there can be a scary side to that too. Sometimes you may find family and wish you never did. They may be a bunch of sleazebags. I've heard enough stories of bad relatives to know that sometimes you wish you weren't related to some of them. By finding them you are aquiring these relatives and bringing them into your life. They may be criminals, drug addicts, somebody who will constantly hit you up for money, or steal from you. It's a risk. Watch Jerry Springer and wonder what it'd be like if those people were related to you. Who knows? They may actually be. We got lucky.
As for my wife, she's been hands-off. I think I was more excited about finding them than she was. Since finding them over 3 years ago, she's had no particular ambition to visit them aside from an event here and there. I think her sister was excited because she always wanted a little sister, but my wife seems satisfied with the family she was raised with. She hasn't even met her brothers yet. And it's not because they're bad people. I don't understand. I'd love to find out I had more brothers and sisters - people like me. But it's personal and it's something that didn't happen to me. So I can't truly understand.
Good luck in your search and I hope it ends well.