discussing genealogical trees, one may also use ordinals instead of multiple "greats"; thus a "great-great-grandfather" would be the "second great-grandfather", and a "great-great-great-grandfather" would be a third great-grandfather, and so on. This system is used by some genealogical websites such as Geni. One may also use cardinal numbers for numbering greats, for example, great-great-great-grandmother becomes 3×-great-grandmother. Individuals who share the same great-grandparents but are not siblings or first cousins are "second cousins" to each other, as second cousins have grandparents who are siblings. Similarly, "third cousins" would have great-grandparents who are siblings, and "fourth cousins" would have great-great-grandparents who are siblings. Etymology The use of the prefix "grand-" dates from the early 13th century, from the Anglo-French graund. The term was used as a translation of Latin magnus. The prefix represents a direct translation of Anglo-French graund and Latin magnus to English. In Old English, the prefixes ealde- (old) and ieldra- (elder) were used (ealdefæder/-mōdor and ieldrafæder/-mōdor). A great-grandfather was called a þridda fæder (third father), a great-great-grandfather a fēowerða fæder (fourth father), etc. Variation maternal grandmother: mother's mother. maternal grandfather: mother's father. paternal grandmother: father's mother. paternal grandfather: father's father. Involvement in childcare Grandparents are changing their roles in contemporary world, especially as they are becoming increasingly involved in childcare. According to a 2012 study based on 2010 census and survey data, around 10% of children in the U.S. live in a household including a grandparent. Of these, approximately a third live in a household consisting of two parents and a grandparent. Likewise, more than 40% of grandparents across 11 European countries care for their grandchildren in the absence of the parents. In Britain, around 63% of grandparents care for their grandchildren who are under 16 years old. Grandparent involvement is also common in Eastern societies. For instance, 48% of grandparents in Hong Kong reported that they are taking care of their grandchildren. In China, around 58% of Chinese grandparents who are aged 45 or older are involved in childcare. In Singapore, 40% of children from birth to three years old are cared by their grandparents and this percentage is still increasing. In South Korea, 53% of children under the age of 6 years old are cared by their grandparents. Therefore, grandparents taking care of their grandchildren has become a prevalent phenomenon around the world. There are a few reasons why grandparent involvement is becoming more prevalent. First, life