The incidence of 7.8% ASD in gender identity clinic referred children and adolescents is ten times higher than the prevalence of 0.6–1% of ASD in the general population (Baird et al. 2006; Fombonne 2005). This important finding confirms the clinical impression that ASD occurs more frequently in gender dysphoric individuals than expected by chance. [Source]
In my experience in discussing sexuality with support groups I admin on, I can tell you that from the ASDers I know (ASDer=person on the Autism Spectrum), most are non-conformists in life. Many do not fit into stereotypical gender roles. While there is a greater percentage of asexual individuals, there is also a greater percentage of LGBTs, as well. For those that have more conventional sexuality, there is often less convention either within the roles of their marriage or in their family dynamics.
Sexuality has largely been ignored in studying of ASDers. One reason behind this was a long standing and perpetuated myth that autistics never held relationships successfully. There is still an often spread myth that 80% of ASD marriages end in divorce. In reality ASD marriages tend to fall into the same stats as neurotypical (non-autistics) marriage.