I have a 6 year old and a 2.5 year old. They both know I smoked. I smoked in the car and outside, but when we lived with my wife's mom for a while, I smoked in the house since her mom did too. I've never hid my smoking from my kids, and I'll never hide my vaping either. When my dad claimed he quit (but really didnt) and was hiding it from us, it created loads of problems. I never want to do that to my kids.
I vape in the house, in the car, wherever I am really. My kids find it fascinating that I don't have to go outside anymore. I even vape if my daughter (the 2.5 year old) is on my lap.
My kids call my vaporizer a cigarette simply because it's easier I guess lol. They'll get it for me when I ask, but they know not to touch it otherwise.
As for when they're teenagers, I started smoking at 13-14. I've been a pack a day smoker since day one. Having asthma, it really was stupid. That being said, if either of my kids come home smelling of smoke even once, that's the day they're getting their own PV. I will not have them smoking, knowing how bad I screwed up my own health. I will also never be a hypocrite, so I can't justify "forbidding" them when I did it. If they want to smoke, they're going to vape.
The ingredients in E liquid are found in food, naturally. I highly doubt that combining and then vaporizing them is the secret to anything worse than the carcinogens in cigarettes. Just on my personal experience, I feel a MILLION times better than when I was smoking, and I would have absolutely zero problem with my kids vaping.