When did you first try Lisp seriously, and which Lisp family member was it?
Interlisp 1986, Scheme 1987, Common Lisp 1988. The most important dates are 1988 (stayed some weeks at Xerox PARC and learned to love CL) and 1997 (started using CL in commercial projects).

What led you to try Lisp?
In 1986-1988, I had access to a Xerox Lisp Machine. I then used Common Lisp for academic work at the universities of Oslo and Saarbruecken (both research and teaching) from 1988 to 1994, then only for infrequent personal work from 1994 to 1997, until Erik Naggum encouraged me to try it for commercial work. (I had been afraid of making my employer even more dependent on me than they already were at that time, but this turned out to be an unfounded fear, since, after starting a large lisp-based project, we had no problems hiring a couple of lisp programmers a few months later)

What other languages have you been using most?
Chronologically: Simula, Fortran, Prolog, Pascal, Perl

How far have you gotten in your study of Lisp?
I hack lisp for a living since 1997, but I never stop learning :-)

What do you think of Lisp so far? The only real disadvantage of lisp is that you never want to go back to any lesser language.