Yes, my adoptive parents had their names put on my birth certificate. I have contacted the attorney, the delivering physician and the harris county family court that handled the adoption. Records at the attorney and doctor offices have been "destroyed". I haven't been able to go down to the courthouse yet, due to my schedule and they hours they're open. I have sent notarized waivers of confidentiality to all three places (doctor, attorney, court) to put on file in case any of my birth family tries to find me.
Since my birth was in 1972, it's not listed in the Texas Birth Index - they started that in 1973. I am listed in the Texas Birth Book, but under my adoptive parent's names. I did find, however, a BC number that's one digit off from mine, in the "A" section. This leads me to believe that maybe my birth mother's maiden name started with an A.
I grew up as an only child. The siblings I mentioned, are my birth mother's additional children she had after me. I don't know who they are. The state of Texas has only told me that one of them, a brother, died when he was 29. They won't tell me his name, nor the names of the other siblings (or their genders).