A blog post and a tweet by Ido Amin caught my attention.
Merging ancestry tree websites like Geni with Facebook would be considered normal in most world cultures
From a pure IT perspective, this would be true. Merging two, or more, data sources for better consistency and accuracy seems to make sense. That is, until the human factor and terminology kicks in. Does a Facebook family mean the same thing as Geni family? Do you store and use the same types of information on both services? Do you want to share that information across sites? Will Facebooks track record with privacy be consistent with that of Geni?
Genealogy is complex and sensitive. Geni does a good job, at least in my view, to manage this, primarily by providing the final say on data to the person who is represented by this data. This is not to say that there aren't issues with data management, but the Geni approach of "better safe then sorry" is very different from the "better ask forgiveness then permission" approach of facebook.