From Sarah Woodbury's website: Romance and Fantasy in Medieval Wales
On the use of the word ‘gotten’
Several UK readers have wondered about the use of the word ‘gotten’ in my medieval mysteries. Since the word is not in common usage in England right now, it seems odd to them to read it at all, and a glaring ‘Americanism’ in a book set in the medieval period. At first glance, this might appear to be yet another instance of ‘two countries separated by a common language,’ but as it turns out, the history of the word ‘gotten’ is a lot more interesting than that.
‘Gotten’ is, in fact, an ancient English word that was in use in England at the time America was colonized by the English. Over the centuries, the Americans kept on using it and the English did not.
Origin: 1150-1200(v.) Middle English geten < Old Norse geta to obtain, beget; cognate with Old English –gietan (> Middle English yeten), German-gessen, in vergessen to forget; (noun) Middle English: something gotten, offspring, derivative of the v.
The British author quotes from reference.dot.com, whose the page is now obsolete.
“British English discontinued the use of “have gotten” as a form of the past participle for “get” over 300 years ago. […]. It is now rarely used in the British version of the English language. American English continues to use “have gotten” to emphasis the action performed. In American English language “has got” implies possession. It is assumed that if “has got” is used that it is referencing what the person has in their possession. On the other hand, “has gotten” implies that the person acquired, received or obtained an item.”
In brief, gotten is a perfectly legitimate word with a long and glorious history.