The first song I ever remember hearing, when I was about 2, was Queen's We Will Rock You so that defined my love of rock/punk/metal right off the bat.
When I was about 10 I got Toby Hawk's Pro Skater 2 which had a soundtrack of RATM, Bad Religion and Anthrax. That pushed me towards punk and some metal. After that I explored punk and its roots, discovering The Clash, Minor Threat, Rancid, Operation Ivy, Refused etc.
More recently, when I was 17, I heard Gallows' Abandon Ship which changed my entire life. Since then (I'm 21 now) my favourite genre of music has been hardcore punk. After hearing Gallows, I explored other bands in the hardcore scene as well as a lot of metalcore and deathcore.
My top 3 favourite bands are Gallows, The Gaslight Anthem and Every Time I Die, all thanks to Gallows.