In a conversation with my brother-in-law's wife she told me two things. She is a middle school math teacher in a public school. She said there are two things that all boys should learn before entering middle school.
She said that other boys figure out if the boys know these two things. They specifically seek to find this information out. If the boy does not know these two things they are labeled "through high school graduation" and will be picked on and terrorized until high school is over. She said these are the basis for labeling a boy naive or weak or stupid or gullible or ignorant or sheltered.
1. All the details of sexual intercourse and sexual male body issues (ejaculation, wet dreams and masturbation).
2. The real deal on Santa Claus.
She went on to tell me that before her son entered middle school (fifth grade in their town) they had a detailed sex talk. She said that the child's readiness is not important, it is more important that the child not be pegged and targeted for their ignorance due to anything under her control. She said since she knows that fact about kids in middle school there was no way she was going to send her son off unprepared. For them the Santa talk happened in fourth grade when he had suspicions and asked about it and she came clean.
I also think the reason she converted over to dressing her son in all Hollister and American Eagle clothing (primarily Hollister) is to avoid any negative stereotyping due to him not wearing the coolest trendy clothes.