Not everyone on facebook actually puts their own pic as their avatar.
Hopefully you don't have relatives or friends who incessantly ID you in photos they post....
Many do. Take one of my nieces for example. She photoshopped her face thinner and put it on Facebook. She's about 250 pounds and under 5 foot tall. But it's her face, although slimmer than the real one. Now in her mid-40's, unmarried and having trouble getting dates.