My formal education ended after 6th grade (chaotic childhood, meth house).
At 16 I started earning enough to live on, doing something on my own that was tangentially related to software, math, logic (keeping it vague to protect id). I did that for a number of years, then became interested in programming and a lot of those skills transferred over very well.
I got a formal software job years ago, and have since held a few positions, including senior engineering positions, at some small- and mid-size Bay Area tech companies.
Now I'm being invited to on-sites at bigger companies (Google, FB, Amazon, etc).
I used to be ashamed, but at this point, my academic history has become something I'm actually very proud of. Someday, I would like to be open and "out" about it, but I don't know when (or if) it will ever be safe for me to do that.
It seems like the kind of thing that should be mentioned during the interview process, not after. So my question is: How significantly would this reduce my likelihood of receiving an offer from a major tech company?
So rather than fret over when the last time you sat in a classroom was... Be proud and confident of who you are, what you have accomplished, and what you will accomplish in the future.