My son is like that too. Loves touching something soft,. like my arm or cheek. Look out girls, I hope he can refrain from touching them. Tenacious, duirng teen age years were you able to refrain? (When he was in kindergarten he kep having the imule to touch girls long hair - he's a big fan 
)
Lately, if he mistakenly bumps into my arm, he has to "even it out" by touching the other arm. Hope his hand doesn't mistakenly bump into a girl's rear and then he has to touvh the other side...
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He would wish someone to know that every person should be respected as an individual with ideas that matter, regardless of one's chronological age.
That thing about your son liking to touch soft things makes me think of Lennie from Of Mice and Men by John Steinbeck. He (I think he may have been MR) and George have a relationship where George makes all the decisions and takes care of Lennie even though Lennie has the upper hand physically. Lennie likes to touch soft things, like mice, but he doesn't know his own strength. If he pets an animal and it bites him, let's just say it doesn't portend well for the poor thing. It was the same thing with this woman who let Lennie stroke her hair.
I agree with that thing about people being respected regardless of chronological age. I tell people that I like looking old for my age because then people show me respect more often and I get the weirdest looks. My female friends want to look younger to attract men. I would rather be respected and maybe I could attract older men. And it would be just as well, too. I get along with people who are older than me/seem older to me better than younger kids.
But I wish I could be respected even if it was obvious that I'm not an adult (like in school).