I agree. My theory is that it's mostly genetic and environmental factors just based on my experience. We think my dad's paternal grandfather had Asperger's. A failed marriage, lack of social skills, and a desire to be on his own? Not to mention the fact that he could not hold a job. Very suspicious. My dad has a cousin with Asperger's as well. My dad's side of the family also has a strong history of mental illness, which could be related to the autism. But then my brother got the worst of the autism, and my cousins got the worst of the mental illness (both of them have bipolar disorder). So I think that there's a natural genetic tendency, but that something perhaps in the environment, flips the gene on. My brother had a lot of risk factors. Family history, older parents (my dad was 41 and my mom was 35 when he was born. 35 or older for either parent is an autism risk factor).
I'm just glad he did not inherit the asthma, though my grandfather and one of my mom's cousins are the only men in the family with asthma, so he had less of a risk factor than I did. My family, like I said, is the history of asthma. Great grandmother, grandmother, grandfather, aunt, mother, two first cousins of my mom's, one first cousin of mine, a second cousin of mine...and me. And mostly women. Four generations straight from my great grandmother to me of all women with asthma. My mom got lucky; out of all of us, she is the least severe.