late Middle English: from Old French sorte, from an alteration of Latin sors, sort- 'lot, condition'
The construction these sort of, as in I don’t want to answer these sort of questions, is technically ungrammatical because these is plural and needs to agree with a plural noun (sorts). The construction is undoubtedly common, however, and has been used for hundreds of years. There are some grammarians who analyze the construction differently, seeing the words "these sort of" as a single invariable unit. For more details, see kind1 (usage).