Something about this picture of Jake Gyllenhaal makes us think that he was actually quite a naughty child, and that he's wearing the glasses to throw people off the scent. We think it's probably the cheeky smile. If you've ever seen the 1991 movie 'City Slickers,' you'll already have seen Gyllenhaal looking like this - he played Billy Crystal's son in the film. He went back to school afterward, but he'd already chosen acting as his profession.
It's hard to say what the definitive performance of Gyllenhaal's career has been so far. You could definitely make an argument for the boundary-pushing 'Brokeback Mountain,' in which he had incredible chemistry with Heath Slater. Fans of darker, more arty films would probably point to 'Donnie Darko,' instead. In any event, he's one of the brightest acting stars of his generation, and he's never short of work.