Brennan is a bestselling author, who has been on the "New York Times" Best Seller List for 18 weeks. She is trained in three types of martial arts, has hunting licenses in four states, and has a legally registered gun as well as a diving certificate. She promised to consider becoming a vegetarian after seeing how pigs were slaughtered (which was also the way her mother had been killed). However, in "The Tough Man in the Tender Chicken" (season 5, episode 6) Angela cites health reasons for Brennan's vegetarian diet. Brennan is also a trained amateur highwire performer, and speaks at least seven other languages, including Spanish, French, Latin, Chinese, Pashto Japanese, Norwegian (although she says only "skull" and avers that, as a forensic anthropologist, this is a word she knows "in just about every language"), Farsi, Yiddish, and German. She has also admitted to knowing a bit of Russian. She often says she does not "put much stock in psychology" and makes a point of noting that Dr. Sweets is not a real scientist as he "bases his life on the vagary of psychology and emotions".