Teaching consent is ongoing, but it starts when children are very young. It involves both teaching children to pay attention to and respect others' consent (or lack thereof) and teaching children that they should expect their own bodies and their own space to be respected---even by their parents and other relatives. And if children of two or four can be expected to read the nonverbal cues and expressions of children not yet old enough to talk in order to assess whether there is consent, what excuse do full grown adults have?
Personal boundaries are guidelines, rules or limits that a person creates to identify reasonable, safe and permissible ways for other people to behave towards them and how they will respond when someone passes those limits. They are built out of a mix of conclusions, beliefs, opinions, attitudes, past experiences and social learning. This concept or life skill has been widely referenced in self-help books and used in the counseling profession since the mid-1980s.