To start things off on the right sour note, I'd like to remind you all of why it is that I think that Elly would be completely freaking useless in this situation. The reason why is that most of why she doesn't learn the right lesson from the past is her tendency to regard her own experience as the measure of all things. Take, as a for instance, her insane over-reaction to her children tracking leaves into her clean, tidy home. The thought-process that explains her baffled anger seems to me to go like this:
1) The only reason I used to track dirt into my parents house is because I resented my mother for daring to behave as if she knew what was best for me and loved watching her squirm.
2) My children have tracked dirt into my house.
3) This is because they hate me and get a cheap thrill out of seeing me in pain.
Since it simply isn't in her to realize that her default assumption that everyone is the same sort of defiant monster she used to be growing up, she tends to distort everything her children do into an attempt to get back at her for being a parent because that's what she would have done in their position. This sort of appeal to anecdotal evidence is coupled with a heaping helping of confirmation bias. Let's, as a for instance, explain why she thinks that Mike has a different sleep cycle than she does. A person who doesn't see an ulterior motive in a time signal would have realized that he's simply wired differently. Elly behaves as if he chose to do so to make her life worse, as if he decided one day to say "I know what will ruin Mom's life! I'll train myself to have a different sleep-wake cycle than she does! (Diabolical laughter!!)"
We also have to remember that since she took her sweet time feeling grateful for what her parents did for her, she assumes sight unseen that she's surrounded by clods who don't have it in them to be grateful. On the rare occasions that she sees that this isn't quite the case, her tendency towards ignoring things that tend to make her admit that she's in the wrong cause her to assume that they're either lying or trying to get something out of her.
Now imagine how someone like that would react to the "disappointment" of not having to own horses because the awful child is sooooooo ungrateful that he or she turned out to be gay. Furthermore, imagine that she's the lesser of two evils.