All your friends uploaded their phone books. When you signed up, facebook searched for your number. The nuance with a shadow profile basically comes down to w

All your friends uploaded their phone books. When you signed up, facebook searched for your number. The nuance with a shadow profile basically comes down to when facebook compiles the relationship of your data into a single entry. People think if they do it ahead of time, its weird. People also seem to ignore that facebook BUYS a lot of data, just like many other marketing data conglomerate.