Making more twins

How box jellyfish venom exerts its lethal effect, will the World end, how were the pyramids aligned, why does humid air feel hotter, why does a hot water stream slow after the tap is opened, what causes lights to twinkle, why do humans have language, is there a way to make more twins, where do stepped-on snails go, and why do diabetics sometimes smell like pear drops? Dr Chris tackles another crop of top questions...