Simple question , where did you meet UNIX OS-es.
I started with linux, and then I have meet Solaris and I am all in Solaris right now , almost a year that I am in UNIX, still reading manuals.
My first contact took place about 25 years ago on a system made by Convergent Technologies, it's unix flavor was called "ctix". After that was a short episode with a unix emulator running on PrimOS, the proprietary operating system by Prime Computers.
After that I worked with Sinix for some years, the Unix variant from Siemens, and a little bit with Xenix (SCO).
In 1995 I started to work with Solaris, version 2.4 was current at that time.
Between 1999 and 2001 I had a short encounter with Tru64 (Compaq). Somewhere around that time (I can't remember exactly) finally Linux sneeked into my professional life.
25 years of Unix and still reading manuals 
Not 25 years for me but so true 
First contact I had was with HP-UX and DEC OSF for a short time when I was in the military way back in 1995. After that I had short contact to SINIX, SCO and SuSE Linux while I was mainly administering WinNT 4 servers doing MCSE certification etc.
I was fed up with Blue Screens and the limited capabilities to administer a windows servers etc. So my next job I decided will be Unix/Linux only and I now nearly work close to 10 years with AIX and Linux (SuSE, Debian) - I do not miss the Windows times at all 
I first learned about Linux while obtaining an Associates Networking Degree in 2002. Of course during my investigation of Linux I was introducted to Unix. From there I learned about the history of Unix and Linux, including Ken Thompson, Dennis Richie, and Linus Torvalds.
My first encounter with UNIX(AIX) was two years back 
So much to learn so little time
About a dozen years ago, on an HP system running HP-UX. A little confusing at first, but slowly got the hang of it. Have worked with Solaris since then, and also some flavors that are installed on PC's.
I first entered in the UNIX WORLD (SOLARIS), around 3 years back.I passed my Engineering in 2007 and entered in this field as fresher.Thanks to my Company, Seniors and whole www.unix.com family for sharing there knoledge with me.Its like ENIGMA..., you just try to know and it seems to be endless which makes you to dig deeper and deeper and much more deeper.....!!!!
My first touch was on Xenix on a machine that the company I worked for purchased (an original IBM AT, the first I'd ever seen). I remember the OS install taking forever. Then years later, we moved to HP-UX and converted all of our mainframe applications to run there. Since then, it's been varients of Linux for me when I'm not forced to use M$ products at work.
My first contact was in late '95 during my HTL education, where we had a few PCs running Linux (got me started with Perl and C, too, and sparked my interest in security). Went through a few distributions 'till I tried Debian (Woody), and got stuck there. Tried a few of it's descendants, as well as *BSD and Solaris, and was forced to get up to speed on HP-UX for work (couldn't say that I like it), but none of those held my interest quite as much.
1985 - Unix System 3 on a "super-micro", the buzz word of the day for small computers based on 16bit non Intel cpu's. It had 2x 40mb disks, and 8 serial ports. My customer paid 20,000 for it.
I started selling SCO products (Xenix) in 1986, and sold each new product as it appeared.
My favorite OS though was Univac OS1100. It had the best source control system. Each line of source code contained a field indicating the version that it was added in, and the last version that it appeared in. So that if the current revision of the file was 30, you could retrieve version 25 by simply copying file,-5 to temp. Its TIP (transaction interface program) was remarkably similar to modern web programming environments.
I don't remember the flavor of UNIX but the hardware was a DECSystem10 in 1983.
1983 too, Unix version 7 (TNIX) on a Tektronix 8560, 16 bit LSI 11/23 running at a couple of Mhz, 256 KB RAM, 20 MBytes hard disk, no networking, no graphics, no vi, the only editor was ed, but, at that time, all this was really cool in front of other OSes, especially the C compiler
To put it succinctly: Staples. One copy of Mandrake cost less than a fourth of XP's currently ridiculous price. After several days stuck in wonder-what-this-button-does mode, I decided it wasn't so bad.
In 1999 I bought a SuSE LiNUX 6.2 package, which included 6 CD-ROMs and a nice handbook (520 page). It was my first contact with a UNIX-like OS. In 2000 I had my first contact with a "real" UNIX, namely AIX, although my only task on that machine was to check if a certain process was running. I was mainly responsible for AS/400 and DEC machines back then 
Ah, if that's a qualifier, then my first contact with a "real" UNIX was an old SunOS system at the local university. Students would shell into it and compile programs on it. It got forkbombed pretty regularly.
University, behind a dumb terminal.
My first contact with unix in my college back in 2001 . After that my real love for unix started with Solaris 9 in 2005 . Then started working with solaris 10 and Redhat OS . Still reading the manuals till date.
I got tired of the same old, same old windows operating system. I decided to try Unix out of boredom and it turned into one of my hobbies. I enjoy reading books on Unix. Some of my favorite systems are Openbsd(ALSR<333333) & sabayon. I'm starting a project using a few Openbsd boxes. I'm am off to the library for more books to check out.
I'm a mac user. Opened the utilities folder and saw "Terminal" but was too scared of it to use it. Years later I get a summer job in a university lab where I need to run simulations via SSH (which meant nothing to me at the time). That's where I learned basic commands like cp, mv, ls etc. Being the obsessive person I can be at times I read about UNIX on the web and even bough a book to learn how to use the bash shell and write scripts.