Its a topic that has surfaced in other places but I don't think has been collected in a way that makes it easy to check out which single artist, band or event had such an impact on you that it formed the foundation for your future listening experience and do you still listen to the same genre(s) of music that you did in your formative years, or have you found something new as you've grown and matured.
Should be fun to then go and check them out.
For me, it was Free with the Album Fire and Water.