If we were rating for violence and distressing images, we'd probably want to rate this at least PG-13 because of all the charred bodies now haunting our nightmares. (The 2005 Spielberg film was rated PG-13 and we think it's not quite distressing enough.) But if we were rating for sexual content, we'd rate this a G because, well, there really isn't any sexual content at all – unless you count the fact that the Martians reproduce asexually. (We suppose "asexual" at least has the word "sexual" in it, so that's something.) But seriously, this book is so un-steamy that after the husband and wife meet again (and after she wakes up from fainting), we expect they shared a hearty handshake.