Indeed, well said. Seems just as plausible, if not more so, that the anxiety is a symptom of poor familial aptitude for mathematics than the cause itself. But that's a thoughtcrime these days, so best not mention it ...
But until we know something provable about genetics and mathematical aptitude this line of thought is just hand-waving. You still don't know any better than anybody else why somebody is having a hard time with math.
That's why I said it seems "just as plausible" as the alternative. Its the article that's making the more definitive statements, not me. Besides, I think there's a reasonable amount of science that makes the argument for genetics over nurture quite compelling, but 20 years of malpractice and misdirection in the social sciences obfuscated that.
Ah, but it's only a thoughtcrime if you don't say it, and people call you an idiot for just thinking that.