my mom is obsessed with idea that my 2 y.o. son may have autism

tl;dr Mom thinks my kid has autism; he doesn't. How do I get her to back off?My mom's an anxious person. I have done a shit-ton of therapy to avoid replicating this pattern myself. Last week I had to go out of town for a work event and my mom and my dad came (~6 hour drive) to help my husband (who has been having some health problems).We were very grateful for their help under the circumstances and looking forward to them spending time with our son, who is 2 and some months.Very quickly after she arrived, my mother said that she "had been worried that [Son] might be autistic, but now I can see that he isn't." There's no particular reason for her to be worried about this--he has no autism in his family tree, has been typically developing including all social milestones and a pretty flexible personality, and has a nursery school teacher who was previously a licensed special education teacher for students with autism. My mom has met this teacher in the past and knows that she is sharp and would not hesitate to speak up if she thought there was something to speak up about. But there isn't.Bottom line: kid does not have autism, he's just really obsessed with cars, trains, buses, dump trucks, and elevators right now. Likes the toys, likes seeing them in books, likes identifying them in real life. It's pretty cool actually! Trains are in the lead right now.After I left town for the work event, her anxiety about this topic apparently became so intense that while our kid was doing his current favorite thing (which is watching YouTube videos of trains), she started trying to show him Clifford the Big Red Dog on her iPad. She apparently felt like if he would switch from the trains to Clifford, this would mean he did not have autism. Alas for her gold-standard diagnostic plan, the kid did not switch. My husband said "how about we let him watch what he wants to watch?" and that was that.I'm torn about how to address this with her, if at all. On the one hand I am pissed as hell that she took it on herself to insert a seed of doubt into the way I see my own child. That's not her place and it's not her business and I'm not going to bargain with her about that. On the other hand this tweaks me enough that if I do not address it with her, it will result in us spending less time with her and my dad over the long term--I was in her line of anxiety as a kid and I'm just not willing to stick my kid there. On the third hand, she's nearly 70 and I think she may have no real idea of what the signs and symptoms of autism are or how kids are assessed for these today (I have an assessment tool I could show her, but I think it might only provoke more anxious engagement/negotiation over how my kid would score, which I do not want.)To be clear, if my child showed signs of having autism, that would be a matter of interest and curiosity and I would educate myself about it, but I know many successful adults with some degree of autism and do not consider it worthy of a freakout like the one my mom can apparently work up on the subject. So there is also some ableist/neurotypical bias stuff here that I'm not happy about.Advice, parents? via /r/Parenting http://ift.tt/2pg00MM