This is a series of surveys & evaluations aimed at finding links between psychiatric "disorders", and perfectly normal traits.
The survey and it's evaluation
The most significant here is a strong correlation between red hair & flat foot and psychiatric "disorders", especially with Asperger. There is also a possible link to various autoimmune conditions (especially to Parkinson).
The survey and it's evaluation
The most interesting link is with toe length. Winter-depression also shows a clear link. There is also other possible links, if somebody can find prevalence figures on the other conditions.