Other.
The thing is, that at a certain age that is dependent upon the individual's own physical developmental pace, the child will discover the mechanisms of their own sexuality. Whether or not they are "ready" for this to happen is mostly up to their parents and to their society, but it will happen never-the-less when their body develops to a certain point, and we'd best prepare them for this mentally and emotionally for when this occurs, so that they are not confused, frightened, or easily taken advantage of when this time comes. And these days this time is coming pretty early: between 10 and 12 years old for a lot of children.
It's an illusion for parents to imagine that they can dictate when their chgildren will be "ready for sexuality" by the way they raise them. ll that will happen by keeping them naive is that when their bodies begin expressing their own sexuality, the children won't know what's happening to them, or how to deal with it appropriately, and will then become more vulnerable to accidents, errors in judgment, and the manipulation from others.