If you want him to be "normal" treat it NORMAL. Kids at school will make fun of him and will be a bigger impact on his decision to act girlie or not than what you could say to him. Making him feel abnormal will lead to way more problems in his life than being gay. I live in Utah and have a cousin that recently said she was lesbian. Her parents are super religious (her dad was a bishop and now stake president in their religion) and very conservative. Obviously they wanted all their kids to be "normal" but the worst thing they could do is not be supportive, this would alienate them form their daughter and cause more stress in her life than already placed on her in society.
People who try to "pray the gay away" end up very hurt that they can not change their feelings and wonder why God hates them. Also, not all boys who play with dolls and do girlie things grow up gay. My son lovesloved barbies growing up and is now a star football and rugby player who is obsessed with girls. My friend's son wanted clothes for his "dolly" for his 4th birthday, now rides BMX almost at a pro level and loves the ladies.
Here is a video that has BYU students talk about their experience at BYU and with their family, thoughts of suicide because their parents wouldn't want them to be gay and death would be better than letting people know they were gay.