A slight adaptation of the lookalikes merged with an idea from one of Hbk4894's threads, basically upload a photo of yourself here and post here the age it gives you vs your actual age (if you're comfortable with that) and also who it thinks you look most like. Photographic evidence is not required, but don't expect any one to believe you're a 95% match with Brad Pitt without any.
Anyway, I'll start it off:
Estimated age: 45 (actually 21)
Nearest lookalike: President Erdogan of Turkey (19%)
Edit: Should add that I got 95% masculine, so as others have mentioned, having a beard seems to make quite a difference