Do we have statistics for where lesswrong readers / posters lie on the Autism spectrum?

We had surveys a while back but I'm not sure if that was one of the questions. I'm not sure how useful the direct autistic poll is. We can calculate a lower bound for the proportion of autistic folks in the population simply by taking the number of people who have explicitly declared they are on the autistic spectrum and dividing by active posters. Even that lower bound is far higher than in the general population. (But complicated somewhat by a high proportion of self diagnosis).

What are your thoughts on the relationship (if any) between lesswrong and autism

Overwhelmingly large. It is somewhat of a haven where the worst of what an autistic person hates in discussion is minimized.

(and, perhaps, between rationality and autism)?

Still overwhelmingly large. Explicitly thinking rationality to a significant degree is more or less a cognitive defect in terms of diverging from the usual naturally successful behavior for humans. I expect a clear majority of people that are described as 'rationalists' to fit somewhere on the autistic spectrum, at least in as much as having tendencies that way.