Catenation occurs most readily in carbon, which forms covalent bonds with othercarbon atoms to form longer chains and structures. This is the reason for the presence of the vast number of organic compounds in nature.
the atomic size of carbon is quite smalland also have a valency of four. thus the covelant bond formed by it is exceptionaly strong and stable. thus it can show catenation property to the fullest extent.
Carbon compounds are usually known as organic compounds as all living things are made up of water and carbon. Thus the origin of many organic compounds is that they are produced by living organisms.