so far it seems ticklishness is part of some genetic heritage so it goels along from parents to their sons. Of course as all genetic heritage, there´s only a chance that the same thing will move from father to all his childs so it´s all a bit arbitrary.
In this way, seems people with fairer skin tend to be more ticklish, it seems something like the way skin interacts with sun. It´s common sense most redheads need to be extremely carefull with the sun. blonds come next, but people with brown hair and green or blue eyes can sometimes have also a vary fair skin, something near blonds or redheads. Then there´s also different sensibilities to different kind of touches so you could find someone who is in truth unbearably ticklish and not be able to tickle him/her cause your just missing the spots or the way to touch them.
For instance, I myself have dark brown hair, but green eyes, in summer they get very light green. I can assure you I need to use protection with high sun/factor values and.....I´m deatlhy ticklish to some kinds of touch...but not to all. there´s a way to tickle my feet that i´ll go completely crazy and it´ll work almost all over them, tops, ankles, everywhere, people just need to find the right pressure to do it. Many miss it completely and leave considering me a non-ticklish persson 😛
So....one never knows! There are theories stating for hair collor relating with ticklishness but there´s so many things playing there you´ll never know for sure!
But defenetely! Don´t think someone isn´t ticklish simply cause they say it or cause still no one was able to brake them 😛
Half of the people who know me think of me as non-ticklish lol