Autism: Probably not caused by vaccines, mercury, television, or unaffectionate mothers.

Via Nobel Intent, a group of autism researchers has developed a genetic model of autism that comes pretty close to predicting the incidence rates that we actually observe in reality. Many researchers have aspired to this and failed, using single-mode genetic models, but this new study finds that introducing a few very specific assumptions about the genetic character of autism helps:

1. Familial susceptibility to autism is a dominant trait, with offspring of autistic parents having a 50% chance of inheriting it. (Autism is known to be passed on from observably autistic parents.)

2. But, while almost all males who inherit the susceptibility for autism develop the disorder, only about 30% of females with this inheritance do. (Boys are much, much more likely to be autistic than girls, autistic parents or not.)

3. Mutations associated with susceptibility to autism are common in the general population. (Females are very likely to act as 'non-symptomatic' carriers, so when autistic children appear in families with no previous signs of autism, they will often be in sudden clusters (rather than being interspersed randomly). Older parents are more likely to have an autistic child, as older germ cells = higher mutation rate.)

Very interesting stuff, and beats the heck out of the timeworn but still common belief that autism is caused by childhood vaccines. For other hypothesized causes, see post title.