It's not chemicals in the water, what you smoke, what vaccines you took or how often you jacked your bits to naked people. Those are you projecting an issue outwards, looking for something to blame. Something to point your finger at, shake it and say: "This is all your fault!" Plenty of perfectly, healthy, intelligent, sane people do some or all of the above. Any one of those things can be bad if it just consumes you're life, be it by doing it all the time or by spending all your waking hours worrying about it, but none of them are anything to worry about on their own.

Nobody knows what causes any one individual to be below average. For some people it's nature - born dumb, act dumb, die dumb. For some people it's nurture - born fine, raised by idiots on a diet of idiocy and end up an idiot. For some people it's peer pressure - born fine, raised fine, surrounded by drooling morons, no back bone, falls in with morons, becomes a moron. Autism obviously doesn't help.

So life is going to be harder, eh? Sucks. Wallow and complain for a bit, but then you can either shake it off and do your best, or you can roll over and die. I'm going to suggest shaking it off and being harder than the hits. Not much anyone here can do to make it easier or make you feel better except to say: Everyone finds out something about themselves that sucks and makes going forward shitty. Nobody around you is prefect. Even the beautiful, intelligent ones who seem to catch all the breaks and just seem to coast through life have something ahead or behind them that's going to make it hard.

It's no big deal. Water off a duck's back, mate. It won't kill you and, honestly, in a world like this?... 88-92 is enough. You won't need to be amazing at everything, just better than the slop you see around you.