I've been in this situation as well. With my family, they know me and the kind of person I am I love my personal space so they ask first and wait until I say yes. Out and about I had a few encounters with people wanting to touch and it didn't turn out well for them. The first time I turned and grabbed the lady's hair back and said "did I say it was ok to invade my personal space?" She was really apologetic, but I had to explain to her just because you like it doesn't give you free reign to reach out and touch it, you don't see me grabbing randomly hot men do you? Anyway, these days I must look like I'm on a mission all the time and really focused because people don't just grab at it anymore, mostly people will stop me and ask if it's natural and what products I use (I think some of them have children with hair similar to mine or they themselves are considering going natural). I'm all about promoting natural hair but not at the expense of my own!
"The one unchangeable certainty is that nothing is certain or unchangeable."

Hair type: 3C
I am a serial cutter