@CarolynKramer2 CarolynKramer2 I'm sending this to the Adoption group. They would probably be able to help you. Also, keep in mind that sometimes census records have the relationship wrong.
@Adoption and Unknown Family Research
I'd love to help you. Could you give a little more information. What is the sibling's name and his/her date of birth and location? Do you have the PID # associated with this person in FamilySearch? Adoption records can be very frustrating.
My two brother's were adopted by an uncle after my mother passed away. In looking them up I would think they were born to someone 10 years old because that's what their on-line birth record shows. Have to admit I've never found the adoption record and just know from family they were adopted. My brother's and remain close, just have different last names at birth (according to official records)
I believe most adoption records are sealed due to privacy. I will try and help you if I can.
Thanks for contacting FamilySearch Community for help.
CarolynKramer2 (Gee, this is a thread with lots of Carol and Carolyn's responding!) Where was this sibling born? Some birth and adoption records have recently opened. Some states have work arounds to get to records. Is the sibling alive? If so, have they (or one of their descendants) taken a DNA test?
Census records are some times incorrect. Adoptions happened within families. Sometimes, mothers or aunts covered for their unwed daughters and had a surprise 'birth.'
Maybe with some extra details, we can help with some useful suggestions.