My daughter has High-functioning Autism/Asperger's and my son is non-verbal Autistic. They are 5 years apart and couldn't be more opposite in terms of skill sets. My daughter has all the language in the world while my son has none; my son is coordinated while my daughter couldn't be more 2 left footed; my daughter has a great imagination while my son adheres to the literal when it comes to play; and my son can tell voice inflection and body language while my daughter doesn't have a clue. AND, my ex-husband, their father, is high-functioning Autistic.
Yes, in my case it's definitely genetic. lol

I'm hearing of more and more families that have more than one. But I still think there's 4 times more boys than girls diagnosed.

in my case!! my child is an ADHD Autistic!! GOOO ME!!! LOL LOL

If you include ADHD as being "on the spectrum", I think it's extremely common. I know so many families where the older child has ADHD and the younger child has an ASD.

Very...I have two siblings with Classic Autism, a sister with language disorder, and my daughter was just Diagnosed with High Functioning Autism!