My DD1 has autism, she was diagnosed at 3 (now 5).
I am about to start the process of assessment for myself. Because she is identical to me as a child. And since I've found out about her autism so many things make sense to me. I've been on a few courses since and find myself nodding along thinking 'I do/feel/think that too!'. I look round and see DH nodding at me too.
Looking at our families, I think I can see it in older relatives on both sides actually. DH certainly has traits also. We're ok our thirties.
I am co convinced it's a primarily genetic thing.
We have no cousins yet, mine are the only children of their generation but it will be interesting to see in years to come. No one in my family has learning difficulties or other health difficulties, we all seem to be on the 'high functioning' area of the spectrum. Social difficulties with various sensory issues.
I would bet my savings on the fact that there are so many parents, mothers especially, who get diagnosed or realise that they are autistic when their child is diagnosed, like me.