Keep in mind that perhaps the main reason to add the profile of an adopted person to this project is so that, when Geni gets around to adding explicit support for adoptive relationships, it will be easier to "find" such profiles and "fix them up" with whatever new features/capabilities are provided at that time.
I agree that it should be noted Harry Craig III In my own case my entire huguenot ancestry would've been lost if I did not add my father but only added my step father. On my step fathers side I don't know anything and I don't think it's even relevant.
In my case I can only go back to Stephen who is the adopted father of Sylvester and Adelia, which shows their last names as Craig. I also have Census records that give Adelia the last name of Sylvester. I am told their birth place in in Pickering Township, Ontario, Canada. But without their true last name I can not go any farther. I don't have the funds to go pro on any of the sites I'm on, so my record search is very slow coming.