The concept of children's sleep doesn't follow the same rules everywhere.
In the majority of civilizations, nocturnal proximity between parent and child is a given. According to one expert, "In Europe there is a problem concerning children's sleep that doesn't exist in the rest of the world; a baby's sleep is simply not seen as an issue."
In Japan, children traditionally sleep alongside their mother until they're about 3 years old. In China, bed-sharing is the norm, as it is in Oceania, Asia and Africa.