Unfortunately, there are many parents who will not discuss sex with their children, which is why the schools took it on. In Michigan, if you do not want your child to take the class, you can sign a paper to waive the class. The child would then be required to do some type of paper on the subject...which means the parent would have to get involved and talk to their kid.
Sex education was never about "how to have sex" but rather to teach kids what is happening in their bodies when they go through puberty, what happens when they do have sex and some of the consequences. This should not be a course on sexual awareness. In which case, they can do so without bringing up the topic of homosexuality at all.
Discuss the biological facts on physical changes that occur during puberty.
Discuss how babies are made.
Discuss STD's.
Discuss the fact that abstinence is the *only* 100% effective method of not getting pregnant or getting an STD and that while condoms help, they're not a guarantee.
I asked my 12 year old this weekend about what he learned in his "Life Skills" class and it appears I need to go down to the school. They did talk about homosexuality and his teacher put forth her opinion that it was wrong. That if God had intended same sex relationships, they'd be able to procreate. *SIGH* Putting aside my own ambivalent feelings about this subject, it bothers me that this teacher is promoting her own bias when she should be staying neutral.