When I was little, I took encyclopedias. But it seemed like the information wouldn't stick around, unlike the poop I tried to flush away.
Around 8, I stopped reading in the bathroom. My parents pointed out the hygienic implications of poop spores and why it's important to close the lid when flushing. The act of flushing creates vapors of dirty water that will settle on surfaces. Like that copy of Wired you set by the sink.