I'm not sure of the sexes of some of the members who have commented here, but it seems pretty universal that the females believe that it's not unusual that a 12 year-old pass as 18. As a man, I've been checking-out females since I was 11 years old, there are often subtle clues as to physical development. Not often do I see such a young girl with both breasts and hips fully developed. Sometimes in large crowds of teenage girls, (such as the local fairs) I may see one who I assume is 16-17, based on their face and large breasts, but when you see the lower-half, you can see that they aren't fully developed. I could only imagine that a conversation about Justin Beiber and the mall would confirm my suspicion. I think that it's naive to think that a 18-20 year-old boy doesn't know when he's having sex with a little girl, despite her physical appearance. I wouldn't give a guy a pass unless he had some type of significant and well-documented developmental delay.