I really do think people get defensive about parenting issues because we worry that we're not doing a good enough job. If the school system isn't good enough for your child, kickball, then they take it as an implied criticism of the job they're doing. Dumb response, but a very common one.
FWIW, I had the same problem with my mom, actually. She felt that because I did things differently than she did, it was a criticism of the parenting job she did. She fought me tooth and nail, criticizing me quite ruthlessly, on every decision I made that wasn't the one she wanted me to make (or the one she had made with me when I was a child.).
To make a long story short, it all came to a head in what wound up being a very productive conversation. I pointed out that most of my life is EXACTLY like hers--to a frightening degree, really. (Far more than my sister's life, and Mom's not threatened by her choices. Go figure.) The small things Mom and I differ on are not barbs I'm launching at her.
"Did you live your life and raise your kids thinking of your mom and how to irritate her? Or did you just try to make the best decisions you could?" I asked her.
That hit home, and she talked about how she felt her mother had always disapproved of some of her choices and how painful that disapproval was to her, when she was just trying to do her best through life.
Things got better fast after that. She stopped taking everything so personally. We get along better now than we have in over a decade.
I don't know if that lengthy, tangentially relevant story helps, but it was a case where someone was defensive and nasty because of insecurity, and it has a happy ending. So I thought I'd share!
