Question: Anthony Dirrell is the brother of which super-middleweight title holder?

Context articles: Paul Smith (boxer)
James DeGale
Anthony Dirrell
Andre Dirrell
Freddie Norwood
Sakio Bika
Robin Reid (boxer)
George Groves (boxer)
Károly Balzsay
Nigel Benn

Paul Smith Jr. (born 6 October 1982) is a British professional boxer.
 He held the English middleweight title in 2008; the British super-middleweight title twice between 2009 and 2014; and has challenged three times for a super-middleweight world title.
James Frederick DeGale, {'1': ", '2': ", '3': ", '4': "} (born 3 February 1986) is a British professional boxer.
 He has held the IBF super-middleweight title since 2015, having previously held the British super-middleweight title from 2010 to 2011, and the European super-middleweight title from 2011 to 2012.
 As of May 2017, he is ranked as the world's best super-middleweight by "The Ring" magazine and the Transnational Boxing Rankings Board, and third by BoxRec.
 As an amateur, DeGale represented Great Britain at the 2008 Olympics, winning a gold medal in the middleweight division.
 By later becoming IBF champion, he became the first British boxer ever to have won both an Olympic gold medal and a professional world title.
Anthony Dirrell (born October 14, 1984) is an American professional boxer who held the WBC super middleweight title from 2014 to 2015.
 He is the younger brother of 2004 Olympic bronze medalist Andre Dirrell, who is also a professional boxer.
Andre Dirrell (born September 7, 1983) is an American professional boxer.
 He has held the IBF interim super middleweight title since May 2017, having previously challenged for the full IBF title in 2015 and the WBC super middleweight title in 2009.
 As an amateur, Dirrell won a bronze medal in the middleweight division at the 2004 Olympics.
Freddie Norwood (born February 14, 1970 in St. Louis, Missouri) is a boxer in the lightweight division.
 Known as "Lil Hagler", Norwood defeated Antonio Cermeño to win the WBA Featherweight Title in 1998.
 He successfully defended his title eight times before losing his title by a controversial 11th-round TKO to Smoke Gainer.
 Among his notable defenses were a 9th-round KO over former WBC Featherweight Title holder Takashi Koshimoto, a unanimous decision victory over former WBO Featherweight Title holder Julio Pablo Chacón and former IBF and WBA Featherweight title holder Juan Manuel Márquez.
 After losing his title to Gainer, Norwood retired from boxing.
Sakio Bika (born 18 April 1979) is a Cameroonian-Australian professional boxer.
 He held the WBC super-middleweight title from 2013 to 2014, and previously the IBO super-middleweight title from 2008 to 2010.
 In 2015 he challenged once for the unified light-heavyweight world title, and in 2007 won the third season of "The Contender" reality TV series.
Robin Reid (born 19 February 1971) is a British former professional boxer who competed from 1993 to 2012.
 He held the WBC super-middleweight title from 1996 to 1997, and the IBO super-middleweight title from 2004 to 2005.
 As an amateur, Reid represented Great Britain at 1992 Summer Olympics, winning a bronze medal in the light-middleweight division.
George Groves (born 26 March 1988) is a British professional boxer.
 He has held the WBA (Super) super-middleweight title since May 2017, and previously the European, British, and Commonwealth super-middleweight titles between 2010 and 2014.
 As an amateur, Groves won the ABA middleweight title twice, in 2007 and 2008.
Károly Balzsay (born 23 July 1979) is a Hungarian former professional boxer who competed from 2004 to 2012.
 He won the WBO super-middleweight title in 2009 by defeating Denis Inkin, making one successful defence before losing to Robert Stieglitz later that year.
 In 2011, Balzsay defeated Stanyslav Kashtanov to win the vacant WBA (Regular) super-middleweight title, also making one defence the following year.
Nigel Gregory Benn (born 22 January 1964) is a British former professional boxer who competed from 1987 to 1996.
 He is a two-weight world champion, having held the WBO middleweight title in 1990, and the WBC super-middleweight title from 1992 to 1996.
 Additionally he held the Commonwealth middleweight title from 1988 to 1989.
 Nicknamed "The Dark Destroyer" for his formidable punching power and aggressive fighting style, Benn is ranked by BoxRec as the fourth best British super-middleweight boxer of all time.