Journalists and guide books have written a lot of nonsense about the subject of touching the head of a Thai. The truth is that we don't touch the head of anyone anywhere in the world unless we know them quite well. To do so is an act of over-familiarity. It's no different in Thailand. Sure, for the Thais the head is the most sacred part of the body, but that doesn't mean that you can't ever touch the head of a Thai person of equal or lower rank. In particular, it is NOT considered bad behaviour to touch the head of a child or a baby, so long as your hands are clean.