Now deceased, this Lancre patriarch is thought to have been part of an inspired but misdirected naming tradition involving the wider Carter family. He appears as an example of how family tradition eventually becomes folk tradition in Book:The Folklore of Discworld.
"Miscegenation" is an old word, now beginning to fall out of use in English as times and attitudes change, describing a practice formerly much deplored, and in fact formerly illegal, in the old apartheid South Africa and in the Deep South of the USA. It is a word with derogatory connotations for inter-racial marriage, and the consequent entry into the world of mixed-race children. (The corresponding German word is something like mischlingeheit, used by the Nazis to label mixed marriages between Aryans and Jews. The resultant children, mischlinge of various grades and degrees, were faced with fates ranging from being sent to concentration camps, to the comparitively minor sanction of being allowed to live unmolested as German citizens, provided they accepted sterilisation.)
It is something of a mystery as to why this concept should exist on the Disc, a place where mere racism within the human species is almost unknown, and people of all skin colours live more or less happily together, Sergeant Fred Colon's opinions on Klatchians not withstanding. Real animosity is spared for cross-species prejudice (As has been noted, on the Disc black and white live in perfect harmony, and all gang up against the green). Would miscegenation on the Disc, provided anyone can spell it, refer to people of mixed species? After all, we're also told Elves and men can cross-breed - and the result must be pretty loathsome in terms of mental adjustment. In times past, Lancre must have seen a little of this? We also know Dwarves and humans may interbreed - Nanny Ogg is thought to have had a little Dwarf in her, even before Casanunda came along to turn a metaphor into a fact. Nobby Nobbs, at the end of Snuff, appears to have gained a goblin girlfriend. There is even talk, in the city, of a Dwarf and a Troll who are cohabiting....