[bestbyV]

http://en.wikipedia.org/wiki/Foreign_accent_syndrome

Between 1941 and 2009 there have been sixty recorded cases To the untrained ear, those with the syndrome sound as though they speak their native languages with a foreign accent; for example, an American native speaker of English might sound as though they speak with a south-eastern English accent, or a native British speaker might speak with a New York American accent. However, researchers at Oxford University have found that certain, specific parts of the brain were injured in some foreign-accent syndrome cases, indicating that certain parts of the brain control various linguistic functions, and damage could result in altered pitch or mispronounced syllables, causing speech patterns to be distorted in a non-specific manner. More recently, there is mounting evidence that the cerebellum, which controls motor function, may be crucially involved in some cases of foreign accent syndrome, reinforcing the notion that speech pattern alteration is mechanical, and thus non-specific.[4][5] Thus, the perception of a foreign accent is likely a case of pareidolia on the part of the listener. So she doesn't technically have an Irish accent. It's just that the damage altered the way she speaks in a manner that sounds to some people as Irish.

and to be fair, she wouldn't turn Irish until she develops a drinking problem and starts fighting people.