Adoption Records, is this possible?

I know this is probably a longshot but I'm going to ask anyway. My family was recently starting some geneaology research and discovered that my paternal great-grandpa was adopted. He passed away in 1979, his wife in 2002, and 2 of his children (including my paternal grandpa in 1990), and he has only 1 daughter that's alive, but she has never been very close and knows nothing about his adoption. He was born in 1911, so his birth parents are deceased. Do we have any legal rights to access to get any information on his birth parents/family? We want to know for both genealogy and medical reasons (my great grandpa, and 2 of his children died before the age of 70 from different causes. We're concerned about the medical history of his biological family) Does anyone know what information we can get, if any, on his birth parents/family? And if so, how? I'm sure this is probably a longshot since the adoption took place almost 100 years ago and we aren't immediate family, but if anyone has any tips or advise it would be appreciated. Thank you