I suspect I was supposed to be supervised but if my parents were checking up, and, looking back and piecing together things I overheard, I have no doubt that they were, I wasn't aware of it at the time. This gave me a wonderful sense of freedom and discovery, something had been already fed by the household collection of reference books. There was Richards Topical Encyclopedia - an endless joy of history, geography and basic science, not to forget the wonder of Volume 14 which held Greek and Roman mythology (somewhat bowdlerized fortunately given what I learned about this later), as well as nursery rhymes and fairy stories, fables and folk tales and a smattering of other mythology from all over the world. Then there were all the other leisure activities ranging from games and jokes and riddles to magic tricks and much, much more. I was so sad when I found my parents had discarded it in a book cull at some time. I had a look on the net to make sure I had the name right and discovered I was by no means the only one for whom this volume was a treasure trove. There are even copies available on eBay and Amazon albeit at prices I can't afford.
Then we had a huge Websters Dictionary that was too heavy for me to pick up. When I ran out of other reading matter I would drag it from its home on the bottom shelf of the book case and lie on the floor with it just reading words and their meanings. I'll let you in on a secret here. Dictionaries and thesauruses still delight me. Ask me to look up a word and you may not see me again for half an hour. Weird? Maybe but it certainly improves your vocabulary. As well we had several large atlases which were full of much more fascinating information than just maps.
So I was lucky, encouraged to indulge my love of learning new things and my joy in reading. And now I have ended up writing speculative fiction. I wonder sometimes if my interest in such things was primed by these books or whether I gravitated to them because of my natural inclination. I guess it's likely it was a combination of both and I'm grateful however it happened.