There's no real way to answer this. If a parent were the one teaching their child, they could install values and/or warnings (save yourself for marriage, e.T.C). Whereas if a school was teaching it, it's depicted as science. This may be less awkward for the child, but again: Parents can save their kids from making mistakes in life if they personally teach values. However, there's so many parents out there that fail to raise their kids in this aspect of life, so the only way the child learns anything is through school. Ideally, it should be the parents. But in the world we live in, I think both are needed.