I don't base characters off of specific real people. But I do draw elements of real people for my characters. The two examples I would think would be easiest for someone else to guess are: One of my characters is a protective big sister whose little brother is the same age my brother was when I started writing that story (she is the age I was, too). I doubt he'd mind the comparison. And the kid has a lot of differences from my brother, anyway. In one of my stories, the kid has three teachers, one based off of my nice kindergarten teacher, one off of my awful witch of a grade 1 teacher, and one a composite of several somewhat crappy teachers later on. I honestly don't care if I hurt their feelings with the comparison - the only one whose feelings I care about is my kindergarten teacher.
Most people know that Bram Stoker used Vlad Tepes as his backstory for Dracula, but what many may not know was that his personality was based off his boss at the Lyceum Theatre. Using the people around you as models for your characters is nothing new. This is somewhat tricky for me, because I am using my WIP as an expression as to how damaging dogma is in society. I can't do this without jibing at religion to a degree, so instead of naming any in particular, there are elements that are particularly picked on. For example, my male lead, where most of these statements come from, says he doesn't kill, "for ideas that cannot be proven outside the pages of a book," which is pretty much alluding to humanity not proving the existence of deities by the scientific method yet continue to shed blood in their name. There will always be someone who will be upset with your work, so the best thing I can recommend is getting it down and getting some other eyes on it after you have. Ask them about it if you're worried.
I do not base my characters on people I know. But I do emphasize on certain traits of people I observe. I do not sugar coat nor spare anyone from the negative and positives of who they are. It simply is. If you take something from a character and they help you grow for better or worse, then that character has done their job. A character is a being who helps people recognize either negatives in themselves they want to change. Or positives they want to aspire to.
I write to entertain people, so I'm not really looking to write anything that's going to upset people. It depends greatly on your target audience, though.
