Our friend Clare of www.madonnalicious.com has just put online an interesting ariticle from Hot Stars magazine:

Suzi Malin, author of Love At First Sight (Dorling Kindersley, £12.99) believes that decoding the facial features of two people can help explain the mystery of falling in love.
Suzi, a portrait painter has spent years studying facial features and divides the physical connections between couples into three types of of visual compatibility: Echoism, Harmonism and Prima Copulism.
Echoism is a basic similarity between two people, who respond to an 'echo' of their own face. Harmonism occurs when two people's faces have near identical proportions, while Prima Copula couples don't share any likeness, but one is drawn to the other as they are subconsciously reminded of their first love - their mother or father.

Here is her interpretation of Madonna and Guy:
Madonna and Guy have Harmonism and Echoism. The Harmonism means they have the same underlying skull shape, and great symmetry: the same distance between their forehead and the bridge of their nose.
They also have strong chins, which means neither of them is more dominant than the other. There's a small degree of Echoism when they smile, in the shape of the mouth.