Since 65% of the world’s population suffers some lactose intolerance post-infancy, I’d say this is just about the piddlingest of piddles. Though, a large portion of those poor souls are East Asian and thus barely culinarily affected by their digestive shortcoming (hooray evolution!).
Such trivial hyperbole, of course, is meant to stress the dangers of designer babies. If we allow selective abortion for Down Syndrome where do we draw the line? Who is anyone to tell me I should value mental capacity over dairy capacity in a child? Though, honestly, I’d rather reroll my procreation for super-powers instead of handicap avoidance. Like super-tasting. Or a sweet-ass prehensile tail.