Perhaps your vision of having a consensus on a question is not far away from others vision of having proof of harm on a specific topic. At least, I assume that

Perhaps your vision of having a consensus on a question is not far away from others vision of having proof of harm on a specific topic. At least, I assume that the people you want to give the freedom to decide matters by themselves, are also people who would accept changing their mind (at a greater scale changing the consensus) when faced with credible facts going against their beliefs. To take your “when you should tell how babies are born” example, I think we agree at some point kids need to know. There is no consensus on when it should happen exactly, but we know a portion of the kids will have life or death issues if it’s not done at puberty. As I see it, idealy we’ll want to put laws to enforce sex education at puberty, and let parents do what they want before that.