Why don't I react to my friends tickling?

Question

Whenever my friends try to tickle me, I feel nothing. My brother, on the other hand can tickle me real easily and so can my father. My friends always wondered why I'm not ticklish.

Answer 1

It could all be just as the previous poster suggests; there are people like that.  There are also people the other way round, as it were.  If you were such a person, you would be too comfortable with your friends to have much reaction to their tickling, as it would not go deeply with you due to their less thorough familiarity with you, whereas your brother and father know you so well that they can really get to your essence, thus rendering you vulnerable to their ministrations.  Perhaps your reaction to being tickled by strangers could be definitive.

Answer 2

You might not feel comfortable with non-family members touching you in that manner.  You may perceive the attempt to tickle as an attempt to impose dominance or will over another person.