The trickle down effect of trust

Its safe to say that I don't live in the most exactly safe city. What I've been noticing is that the weariness I have of people while walking about on the street is the exact same sort of demeanor I use when attempting to build friends or relationships. I have a wall up and am generally untrusting of people's intentions. I don't want to get hurt emotionally the same way I don't want to get mugged, so I tend to divulge little information. I can't get it out of my head that I should be cautious of people, but I think I tend to dismiss those quite a bit that genuinely do have good intentions.  

I wonder if I grew up somewhere else if I would be different? I genuinely believe that good people do exist, it just can be difficult for me to let my guard down