[4] McGuinness, who is half-Korean and half-Irish,[5] was born in Killeen, Texas, and was raised on Long Island in Islip, New York.
[11] After Darren Starr saw her short film, he hired McGuinness for her first series writing job on Miss Match, starring Alicia Silverstone.
[5] Since then, McGuinness has written on shows including Mercy, 30 Rock, About a Boy, Friends From College, Forever (2018 TV series), Ramy, Stargirl, and Life & Beth, where she was also an executive producer.
[12] She joined the staff of 30 Rock in 2011, which ultimately led her to share in the series' Emmy, WGA, and PGA nominations.
[14][15] In 2016, together with Game of Thrones executive producer Carolyn Strauss, McGuinness worked with HBO to develop a comedy series based on the novel Prep by Curtis Sittenfeld.