Pigeon-toed gait in intelligent women?

Bruce Charlton, editor until recently of the journal Medical Hypotheses, writes in his blog:

Pigeon-toed gait endemic among intelligent young women: medical note

I have observed that a pigeon-toed gait is now endemic among intelligent young women (such as students). A pigeon-toed gait means walking such that the toes of the feet are turned-inwards….

Being pigeon-toed used to be rare among adults – more common among children, most of whom grew out of it during their teens….

Yet I would estimate (from casual observation) that a high proportion of intelligent young English women in their late teens or early twenties (something between a quarter to a half perhaps?) now walk with a pigeon toed gait – all the time, with obviously worn inner heels. This certainly was not the case thirty years ago. So what has happened?