Mine so far have been influenced by quite a few different sources. My parents are both Labour voters and both lean in some way towards old Labour, although my mam's a lot more progressive than my dad, and I definitely picked up their socialist leanings from an early age. Then, by the time I was in Sixth Form, my politics teacher was an old-school Labour lefty communist type while most of my peers were left-wing supporters of either Labour or the Lib Dems. It was pretty much about that time though, as a result of my own research into political ideology and my peer group that I became a pretty hardcore left-wing communist. There was a little group of us through the end of High School and through Sixth Form and all of us fell into that ideology. Some of us were further along the scale than others, with me and my best friend at the time essentially supporting Kropotkin-esque Anarcho-Communism as far as we could effectively realise it in real life (which, honestly, was not at all but the though was there).
By the time I got to university, I was keeping up to date with all the political happenings across the world, and realised I was mellowing out a lot more. I'm still a lefty, and I still broadly subscribe to the ideals of communism, but they're tempered. I can look at the ideas I held and see the flaws, and can happily consider other ideologies. I'm just a kind of vague socialist lefty type.