Kayla 14 for sure, maybe 13, and 12 really depends on the 12-year-old. I would be most leery about the child abuse; there's also very, very vague implications of sexual assault in the second book, as well as suicide. Overall this deals with some heavy stuff, but not in a really hands on way. I definitely read worse when I was 12, but like I said, depends on the kid.
Jody Schaefer I don't know about 12 but definitely 14 or 15. The characters are high school aged. There's talk of drinking and there's mild violence but otherwise it's pretty harmless. I still don't think I'd hand it to a 12 year old.