Well, I'm glad I could help out. I was actually doubtful I'd have anything useful to say, but (as is often the case) my unconscious mind was doing a better job of working the problem than my conscious was.
Been using it for half an hour and I still like this webchat interface better than any I've ever seen. Someone did an unobtrusively superb job of design here. I'd rather like to know who.
Can you change the display title of the forum? Because another way to reinforce the message would be to have it read not "Parenting" but "Tools for Parenting".
So I'd say start by having a FAQ entry explaining what "mechanism, not policy" means. You have a high enough percentage of techies that you can usefully point back to the programming usage, and that may even lend it some authority.
So, if someone posts asking "what's a good starter type of firearm for a child?" and someone else starts in on "it's a bad idea to tech kids about firearms", you can say "mechanism, not policy".
So I suggest as a first step inventing some kind of tagline you can repeat at people. "Mecanism, not policy" may be too dry and techie; I don't know, not familiar with the demographics here.
The though you want to convey to people who join here is, I think, a lot like the rule in programming that you want to separate mechanism from policy. Mechanism is what enables you to do thing; policy is your choices about what you do with the mechanism.