Well, you are actually correct there

My current job is building and testing linux distributions. (that's the 2 inhouse distributions I mentioned...)
As for the other ones; Debian was my first love and I still have few running Debian machines. Ubuntu and Fedora are widely used in the company so I also have machines I run them on. Gentoo was a kind-of sideline I installed some years back on a desktop that I still use daily, just as I wanted to learn how it is different from prepackaged distros.

If we go down the dark history, my first distribution was Slackware way way back in the dark ages, and my late father-in-law used to run SuSe for at least ten years...