A little later than some here, but my entry was via Phil's solo stuff. Not hugely, in that I was a massive fan then got into Genesis, but I was just more aware of Phil on the radio growing up. My earliest memory was You Can't Hurry Love on the radio, then Against All Odds, then Another Day In Paradise (with only one out of those three being returned to regularly some 30+ years later). It was his Serious Hits Live album that I first listened to from beginning to end when I was about 12 or 13, which happened around the time that No Son of Mine was released, and I became hooked instantly.
From there it was a quick progression. I worked backwards a couple of albums, before finding SEBTP in my dad's vinyl collection, and tapes of one of the versions of FGTR and W&W, a strange combination as he was never really a fan of their music. I couldn't get into W&W on first listen, nor on many subsequent listens, but that has changed considerably now. SEBPT I played a lot - the only vinyl experience I can recall in fact - and Firth of Fifth has remained at or near the top of my Genesis tracks ever since.
Foxtrot was next. I remember being crushingly disappointed, having bought the tape and got home, to find it was faulty in some way. Getting in to town back then wasn't a common thing, but I convinced my mum to take it back and get it replaced the next day. Only problem was, I told her the wrong music store, but she argued with the person there until I think he just gave up and gave her a new one. It's a bit hazy after that as to what came next - I think ATTWT, ATOTT, and Abacab, with the rest following very quickly after. No rhyme or reason to the order, largely what the record store had in at the time, and little means of researching the band back then, so I had little idea early on which incarnation of the band was playing on which album I was buying.
I feel like I've missed out by only getting into Genesis so late and quite envious of many of you who have memories of older tours. I do count myself fortunate to have seen them live a couple of times though. Also my school friends were getting more into grunge and other stuff that does nothing for me, so I had no one to share my love of their music with, and Phil started to get particularly bad press at the time, so it wasn't "cool" to be a fan of either as a teenager. Still, despite flirting with a few other bands and artists over the years, it's Genesis that I always return to - nothing and no one else ticks as many boxes for me as my first passion.