I agree with your analysis of why people act as they do, but they might act differently if they were better-informed. If people were more accepting of the heritability of intelligence and the relationship between intelligence and academic achievement, they would be more fatalistic and worry less. When the media stresses environmental explanations of why some kids do better in school than others, parents feel pressured to create the perfect environment.
I don't think they'd act differently. I think that people actually
do realize that talent (including IQ) is largely inherited, whether they like to talk about it out loud or not. A child's abilities are reflection of his parents' abilities. This, in part, is driving the pecking moms (and occasional dads). Remember that blog post that Joyce Slaton wrote? She was the one who wanted an "Amazing Super Child who was going to prove to the world how 5-star my DNA is...."
What are braggart parents doing but putting their DNA and superior parenting skills on the table to show them off? Being proud of your child is a wonderful healthy feeling, but there are some parents who go past the wonderful healthy aspect of it and head into getting territory that's not healthy.
Say a group of insecure people are jockeying for position in the DNA/parenting skills hierarchy. Junior's skill acquisition is the currency they use to climb the tower. They're all in roughly the same place, and getting into the highest group is a reasonable possibility with a bit more of the right kind of effort.
Then someone else comes along and says that her five-year-old is reading
Magic Tree House research guides....well, other parents could react as though someone just, emm, peed on their DNA and parenting skills. I'm not trying to be crude here. I can't think of a better way to say it.
And IMO, announcing that, "Oh, we don't push her, she pulls us --- she just loves to read," can make things worse. It says that the other person's superior parenting skills aren't so superior after all.
Added: I'm not trying to excuse the mean-spirited reaction described in the OP. I'm just trying to find a way to explain it.
