I have eight kids, five boys and three girls. I have four boys (what a surprise!) that I could have "labelled," and one of the girls.
Now, it's possible that there's been an increase in genuine autism cases. Vaccines might be an issue; I don't find the evidence for or against that possibility to be sufficient.
Additionally, television and video games, institutional child care, and other factors may contribute to some symptoms.
However, when you read the criteria used for "diagnosing" autism and ADD, you find that any male over the age of one could be "diagnosed" with one or the other. Doesn't want to sit silently in a chair for six hours? ADD! Learns some subjects more easily than others? Autistic!
Lots of factors going on here other than vaccines (the only control studies out there show no connection - apparently the onset of the first symptoms of autism often coincides with the age when vaccines are customarily given - post hoc proper hoc strikes again.) A few that come to mind:
The definition of "autism" has expanded dramatically. When I was a preteen/teenager I knew a couple of families who had autistic children. In those days, it wasn't a question of "poor social skills" or being a little geeky - one of those boys is 40 and still living with his parents, and when they die he'll have to be institutionalized. Nonverbal, no interaction with anyone (even his parents), spends his time being hyperfocussed on shadows on the wall or cracks in the sidewalk . . . it's just a dreadful situation and there doesn't seem to be anything anybody can do for him. But there is absolutely no question that he's autistic . . . now you see kids labelled "autistic" who are just, as you say, a little on the weird side of normal. Shoot, if that's the criterion you might as well go ahead and declare my entire family autistic . . . we used to be known as "eccentric."
Of course, in those days there was also a stigma attached to autism because it was thought to be a psychiatric problem caused by a cold, unemotional mother. Which tended to hold down the number of cases, nobody wants to be blamed for such a catastrophic problem. Now, the schools get money and parents can get SSI for children with the diagnosis. Which tends to increase the number of diagnoses.
To some extent, I think I'm glad that my daughter has the MRI that shows brain damage. I wonder what kind of "diagnosis" she would have had.
We knew she could have brain damage when she was a baby, but we didn't have the MRI until she was 3.
I had one special ed teacher tell me that she thought my daughter was a selective mute. Basically she thought my daughter could talk, but she was choosing not to. What an idiot.
I also loved the psychologist that I went to when my daughter was about 3 or 4 and totally non-verbal. My daughter had (and sometimes still has) terrible tantrums. I wanted to find some tips on helping her with the tantrums. So the psychologist gives me a book that tells me that you need to communicate better with kids that have tantrums. I needed to talk more to my daughter, and I needed to encourage her to talk.
If the talking didn't work, well there was medication.
I couldn't talk to my daughter, and I didn't want to medicate her.
What I don't like is that professionals don't give you any other advice on how to handle situations. I honestly think calling Nanny 911 would have been better. I bet she could have given me better advice.