In Which, Due to Various Mis-Fortunes and Unforeseen Responsibilities Springing Out of The Wood-Work Like So Many Nagging Termites, a Most Abbreviated Post is Posted, For Your Slight Enjoyment
Nerd appears to be the invention of Dr. Seuss, although in the context he uses it refers to one of his standard fantastic animals
Dork is, contrary to rumour not the penis of a whale, but simply a mid-western re-con-figuration of the word dick.
Dweeb is possibly a result of appending dw to the past derogatory feeb, but like much slang, little can be said for sure.
Twerp is decidely uncertain, the oldest printing one can find utlizing this term is a handbook of sailors jargon, and as I may attest, the Gods only know from what multitudionous sources they derive their cant.
As a side note, the OED allows one to historically list various synonyms, taking dork as a starting point, one ends up viewing such past insults as hinderling, fouling, dogbolt, pilgarlic, skit-brains, ketterel, skybald, mumpsimus, smatchet, scabship, polecat, cittern-head, petti-toe, mustard token, snotty nose, shag-rag, glow-worm, whiffler, snool, ramscallion, spalpeen, tripe-hound, shite-poke, lint head, squiff, and the quintessentially yiddish schmegeggy
