In many countries in Europe, as well as in North America, we don't even ask the question any more: a child should sleep alone and everybody should do what they can to help him, even if the price you have to pay is a succession of sleepless nights. Many pediatricians recommend stringent separation, which could pose a risk of serious disturbance to the child.
Today, supporters of bed-sharing are making themselves heard. Organized groups are active in the United States, though less so in Europe. They advocate the benefits of co-sleeping for the whole family. But between the detractors and supporters of bed-sharing, there's a lot of judgment and divided opinions.