An aside: accessories

Observing the crowd after last night's concert confirmed something I've noticed over the years: a disturbing number of Flemish people wear rectangular glasses similar to Bart Defoort's, yet I don't think I've seen any Walloons wearing them. In fact, in the subway they are an almost fool-proof way of distinguishing Flems from Walloons (you can then verify by seeing which language the newspaper they're reading is in). I've also found that, generally, Flems are more likely to sport an "eccentric intellectual" look. Why is that?