From my observations it's true. We are too uptight, strict by the rules and rarely become laid back about stuff.
I've loosened up from past experiences and I would say that I am more lax then people who don't have Aspergers.
When I talk to fellow Aspies I see it a lot and I kind of feel put off by their strictness in everything and I can actually relate to people who do say "Why are you so serious all the time?"
I still act serious on things I don't like, but overall, I let things slide as it really doesn't bother me any more. People with As should do the same sometimes considering where priorities lie.
I can understand things like education, politics and family being a serious thing, but trivial things such as someone being misinformed, mis-spelt something incorrectly shouldn't be taken as seriously, as people really are not trying to do it on purpose.
The too quiet comments I can live with too, as that is just how I am.
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Just a guy who gives advice and talks a lot.