Why is it that autism can not possibly have any other cause than genetics?
"Because autism runs in families, genes likely play a role. Other risks include:
Mothers and fathers who have children late in life
Pregnant woman who drink alcohol or have conditions like diabetes and obesity
Pregnant women who take antiseizure drugs
Untreated phenylketonuria (called PKU, a metabolic disorder caused by the absence of an enzyme) and rubella (German measles)
There is no evidence that vaccines cause autism. The exact reason why autism happens isn't clear.
The usual signs of ASD usually show up when a child is between 2 and 3 years old, but experts think it begins much earlier, when the brain is starting to develop. Experts don’t fully understand what causes it. It seems to be genetic, mostly. And it usually involves more than one gene, so it’s complicated."
From a WEBMD page
It's something you're born with or first appears when you're very young. If you're autistic, you're autistic your whole life. Autism is not a medical condition with treatments or a "cure". But some people need support to help them with certain things.
From NHS page
So, there's every chance that there are multiple causes prior to birth (e.g things during pregnancy that affect a foetus that need to be further studied) but all signs point to it being a condition that develops in-utero and has a change in neurological physicality. AKA, not vaccines and even if vaccines had a cognitive effect meaning they exacerbated autistic behaviours, odds are there would still have been underlying autism that would have reared it's head and some point anyway. So at worst, a catalyst not a cause.
claim that both these people have a gift that should be celebrated and not wished away...
I'm not claiming it's a gift. I've said previously that if I had had no experience of autism, odds are I would probably not want to have it (because it is a disability, irrespective of your use of "functioning" labels). However, for the children and adults who are already alive and have autism "wishing it away" is not conducive to anything because a) they are already alive and b) they already have it. I empathise with the desire to give your child a better life and want them to have an easier time, but that comes with the practicality of making life better for them as an autistic person rather than trying to make them neurotypical.