Sexual Education is something everyone learns at one point or another in their lives so whether it's taught at home or at school should not matter. Some parents say they would rather teach their children at home but the vast majority most likely will not due to it being too 'awkward'. 
These protesting parents also need to take into consideration that they are depriving their children of the fact that they need to learn these important aspects of life. Not only will they learn about it but they will experience sexual tendencies for themselves. 
Another important factor about students learning about SexEd is they will understand what is good and bad, including rape and sexual assault.  Instead of teaching students that homosexuality is wrong, they should focus on teaching them that no one is "asking for it" because rape is rape, and it's wrong.