Earlier quoted context omitted.
I believe the paper the parent comment linked used 'thick skin' as a metaphor for pain resistance, not literally deeper epidermis.
I am pretty sure this is literally about skin thickness. Here is the list of false beliefs polled: Blacks age more slowly than whites; Blacks’ nerve endings are less sensitive than whites’; Black people’s blood coagulates more quickly than whites’; Whites have larger brains than blacks; Whites are less susceptible to heart disease than blacks; Blacks are less likely to contract spinal cord diseases; Whites have a bet…
I don’t know how you’d go about testing some of those and many shouldn’t matter to doctors, but I personally think the differences between us are fascinating.