‘…there might be something more fundamental about the way clowns look that unsettles people.

In fact the strongest factor we identified was hidden emotional signals, suggesting that for many people, a fear of clowns stems from not being able to see their facial expressions due to their make-up. We cannot see their “true” faces and therefore cannot understand their emotional intent. So, for example, we don’t know whether they have a frown or a furrowed brow, which would indicate anger. Not being able to detect what a clown is thinking or what they might do next makes some of us on edge when we are around them….’

— via The Conversation