^^^^ I raised two great boys with few issues. One, I just had to say it once and be firm. The other, took a little more effort.
Education is a big part along with earned trust. Today, unlike then, you have lots of good ways to secure a weapon and still have reliable quick access if needed.
When toddlers are the subject, they can't comprehend using a toilet let alone what a gun is. Not worth the risk in my opinion with today's many options.