A personal name is the proper name identifying an individual person. It is nearly universal for a human person to have a name; the rare exceptions occur in the cases of mentally disturbed parents, or feral children growing up in isolation. A personal name is usually given at birth or at a young age. The Convention on the Rights of the Child endorses personal names as a human right. The details of naming are strongly governed by culture; some are more flexible about naming than others, but for all cultures where historical records are available, the de facto rules are known to change over time.