I happened to encounter two identical twins sitting next to each other on the tube the other day. They were fairly atractive young women - Americans, I thought - and were the spit of each other to look at. What was interesting was that they wore exactly the same clothes, but in different colours. Matching checked puffa jackets - one in pink, the other in purple. Tracksuit bottoms, trainers, carefully applied lipstick. Eerily similar, but each with a unique hue. It was almost as if they wanted to make a statement about how they were separate people.
To the keen psychological observer, however, the conscious display of individuality didn't cut any ice. Both girls crossed their right feet over their left feet in exactly the same way and spent the whole trip on the Northern Line in silence, fiddling with their long hair. Biology beats wardrobe every time.