Your dad sounds like a guy after my own heart. I have been known to let lizards prowl about in my places too - including a couple of very large ones here at our present place amongst the trees. They aren't very compatible with cats and indoor dogs though - who tend to see them as a comination of toys and food.
Heck, I even let benign spiders roam about - or else gather them up and put them outside. I am not nearly so kind with ants, flies and gnats though.