The mind of a wizard is more open to the more esoteric elements of his surroundings - this is why he is able to perceive the weave of the Great Tapestry that is the multiverse, and pull at the strings. This increased sensitivity can manifest in several ways.
Surnames: Most surnames fall into one of four categories. Patronymic surnames such as Johnson pass from father to son (literally, 'Son of John'). Occupational surnames such as Cook or Miller stem from an individual's livelihood. Topographic names such as Forest or Ford identify habitation. There are also a few surnames that derive from individual characteristics or nicknames...Small and Stern for example.