I actively try to seek out variety in my characters, but of course parts of my self are reflected in them. I'm not always aware of those parts, but I think it's hard to avoid. My perspective on the world and on other people will always be reflected in my work, it's kinda inevitable. ^^
A big theme of my comic is the feeling of rejection and being ostracized - be it by individuals or society - and how the characters craft their identity around that. I personally have dealt with that in my childhood years a lot. My characters go through way more extreme things than I did, but the inherent feeling of "being wrong in the eyes of the people around you" as well as starting to identify with their role as "the other" is still similar enough. The second comic I have in mind will deal with the inner rejection of the self more so than that from the outside - also something I am familiar with.
My characters deal with those things way different then I do. One thing I love about ensemble casts is how you can show people reacting so different to the same problem. But at the core of most of my characters is a conflict that I am deeply familiar with - for better or worse.
Well and sometimes I just give the main character of my comic the same haircut and similar facial structures as me and never realize it until someone points it out. 