I love your listing. I can see, looking at it, why a family might be attracted to stay there. It has a really ideal/All-American vibe. Are you having issues with repeated requests from families and worried that it might impact your response rate, or just trying to prevent potential issues?
I am a parent of children 11, 8, and 5. I am just giving you feedback based on how I would approach the listing. First of all, you have no control over how Airbnb default says "may not be suitable for children 0-12." For discrimination purposes, I think the language has to be that way maybe. Who knows. But for sure that would be confusing to me as a parent because if that was the only statement I would just automatically think, "oh. Well my kids aren't thoes people. I don't actually give a **bleep** whether they are safe at all." For me, a statement like "Keep your little minions out of my precious house!" would be so much more helpful because then I could just scroll on by.
But, given that you can't change that, I think it is really smart that you spell it out in your listing, and have it as part of your house rules. In your listing, you clarify no children by mentioning 1905 house, lead paint, uneven hardwood floors and fireplaces. This seems a bit much honestly. In the historic North End of Boise there are plenty of families residing in houses thusly described,all children alive, well, accounted for. I read that and just kind of smirk, because my kids have traveled all over India without carseats staying in rural villages with dirt floors. You don't have to make an excuse about safety. It's your home. Just say, "Our home is not appropriate for children/families, and we will not accept bookings with children in the party". That is your decision to make, and you don't have to clarify and really it is probably just as well that you don't.
You already have Instant Booking turned off, so that would give you another layer of protection as everyone has to request to book so you don't get any guest surprises. The only thing you might consider changing, is upping your additional guest charge above $5 to something higher. But that is really only assuming that it is a cause of great concern for you that you receive a request/inquiry and have to decline it. Given your house rules, you would be well within your right to refuse to accept a mother traveling with her 12 year old daugher should you choose to do so, so it seems unnecessary if you don't mind telling folks no every now and then.
The only other thing I can think of is we typically book an Airbnb on the fly, last minute, and instant book only so we probably aren't your ideal candidate, but if I was booking your place I probably wouldn't read all of your house rules immediately because they are very LOOOONG. I would skim. It's great that you have the key points spelled out in all caps so my eyes should find the ones that apply to me. However, if I were going to miss something it would probably be things that are placed near middle of list, especially if I was booking on the road with a van full of deplorable children distracting me. (Remember, I would be sorting through 20 listings, not just automatically finding the perfect thing). So, if this is an issue that is really important to you/causing you some grief, you may consider moving the NO CHILDREN UNDER 12 all caps statement further up in the list to position 5, lets say. I can understand not wanting to lead with "NO CHILDREN" because maybe it sounds a little grinchy or something, but really if it helps the intended audience that could actually be a very nice thing to do because it automatically releases us to consider options that are appropriate. You are a great writer, so I am sure you can write it in a way that still sounds gracious/welcoming.