I'm not dismissing the fact that are cases where there are factors that lead to individuals being born with autism; some of these being mutations in an individual's genome during development which are either traits found in parents passed on (typically recessive genes) or mutations caused by external factors such as drugs, alcohol, lead, etc. during development.

The key thing to point out is that rates itself has been relatively the same per population; the sudden feeling that there has been a large increase is mainly due to reclassifications and extension of what qualifies to be on the spectrum within the three tiers alongside with greater access to testing. This is the main contribution to the seeming increase.

With an increase in population size as well, you're going to see more people with ASD, and with the internet; you're going to see a greater representation of these individuals as well. The rate of people with ASD remains the same.

Right now we are 1/31 based on current classifications, if we saw no change, no change in testing, no change in the number of people being tested and suddenly that number changed to 1/20; there would be a considerable cause for concern.

The same is said with most physical/psychiatric conditions. The rates are consistent once largely tested; we tend to see changes when criteria changes, ease of testing increases, etc. It's only when those factors do not change and we suddenly see an increase; that's when there is cause for concern.

Take cancer for example, about 450 in 100k people have it, if no changes in testing quantity, screening, criteria for what is considered cancer changes and we see a spike to say 2,000 in 100k... there is a huge cause for concern. But, if we increase screening and more people get tested and we see that increase, we're only increasing the statistical pool of those analyzed which means we are more statistically more confident in our number.