Do you think sex education should come from parents, school, or a mix of both?Personally, I think a mix. I think sex education needs to include the clinical basics, which can easily be taught in school. How it works, how pregnancy happens, how pregnancy is prevented, how to protect against STDs, the definition of sexual assault and abuse... all basic information that a teacher and/or clinician can present so that kids have the facts.
Sex Ed should also include a moral component, which I think differs depending on the parents, culture, religion, etc. That has to come from home. It's different for every kid, and doesn't fit in a classroom setting.
Kids also need to feel comfortable asking questions. No kid I've met will ask an embarrassing question in front of his friends - but he might to his dad or older brother. If he knows the basics, he will feel more confident in the question, which will make for a more constructive conversation at home.
Neither my family nor my school was at all open about sex education. As a result, I got most of my early information from friends. Do you have any idea how long it took to correct all that misinformation?! Kids are much better off learning it right, learning it well, and learning it as early as is appropriate.