Julia Meuter Meuter itibaren Uspenskiy, Moskovskaya oblast', ရုရှ, 142953
First read this when I was 12, and got hooked. Definitely influenced me in subtle ways that I'm only aware of now as an adult reading the latest installments. Sex education, of course, was part of it...but even more than that, I think there was the whole medicine woman thing and the self-sufficiency and survival thing that really made an impact on my young mind. It also has messages about prejudice and understanding the "other" that I think established themselves in my psyche. It's very detailed, but even as a kid, I somehow never found the details boring.
I loved this even more than Sharp Objects. What a great thriller!