I have always been very fortunate, but then we had both dogs and cats / puppies and kittens in my childhood, and I am the elder daughter, so it was part of my upbringing that when there were kittens, puppies and children under five, one adult always either kept an eye on the youngsters, or on the Christmas tree.
My mother firmly believed that if you cannot hear where a kitten, puppy or todler is and what they are doing, then they are probably doing something they shouldn't, and immediate investigation is called for.
As a school-teacher I have found that precept very useful with children of all ages!
One year our Christmas tree capsized and landed gracefully on the sitting-room floor.
Believe it or not, nothing broke, and happily, our two young kittens were both with us in the kitchen, where they were being fed, as the rest of the family sat down for dinner, and we were three adults who all saw that the kittens were not responsible for the tree collapsing in a faint.
We put it up again and added a couple of guy ropes for safety's sake.