Many more boys are diagnosed with autism than girls; in fact, four times more boys are diagnosed. While the reason for the disparity between male and female autism rates is relatively unknown, there are several theories. One theory is that the possible mechanism for the transmission of autism is on the sex-linked X chromosome, but researchers are still a long way from identifying a simple genetic cause for autism. Females are sometimes thought to be “protected” from autism but the reason remains unknown. The reason for this imbalance between the sexes may be something much simpler; autism presents differently in females. Autistic girls “look” different than autistic boys.