Question: Cassius Marcellus Clay Sr. is the father of this American former heavyweight boxer, younger brother to Muhammad, born in what year?

Context paragraphs:
Brutus J. Clay: Brutus Junius Clay (July 1, 1808 – October 11, 1878) was a U.S. Representative from Kentucky, and a son of Green Clay.  His brother Cassius Marcellus Clay also was a politician in the state, and they both joined the Unionist Party at the time of the American Civil War.

Cassius Marcellus Clay Sr.: Cassius Marcellus Clay (November 11, 1912 – February 8, 1990) was an American painter and musician.  He was the father of three-time World Heavyweight Champion Muhammad Ali and Rahman Ali, and the grandfather of Laila Ali.  He married Odessa Lee O'Grady in the 1930s and worked as a painter and a musician.  He was described as "a handsome, mercurial, noisy, combative failed dreamer" and a "hard-drinking, skirt-chasing dandy of a daddy".  His son Muhammad Ali described him as "the fanciest dancer in Louisville".

Rahman Ali: Rahman Ali (born Rudolph Valentino Clay ; July 18, 1943) is an American former heavyweight boxer.  He is the younger brother of the late Muhammad Ali.

Cassius Marcellus Clay (politician): Cassius Marcellus Clay ( ; October 19, 1810 – July 22, 1903), nicknamed the "Lion of White Hall", was a Kentucky planter, politician, and emancipationist who worked for the abolition of slavery.  He freed the slaves that were handed down as his inheritance from his father.  Those freed slaves were allowed to stay and were paid a wage.  He was appointed by President Abraham Lincoln as the United States minister to Russia during the American Civil War, and is credited with gaining Russian support for the Union.

A.k.a. Cassius Clay: A.k.a. Cassius Clay (styled as a.k.a. Cassius Clay) is a 1970 boxing documentary film about the former heavyweight champion Muhammad Ali.

Muhammad Ali: Muhammad Ali ( ; born Cassius Marcellus Clay Jr.; January 17, 1942 – June 3, 2016) was an American professional boxer and activist.  He is widely regarded as one of the most significant and celebrated sports figures of the 20th century.  From early in his career, Ali was known as an inspiring, controversial, and polarizing figure both inside and outside the ring.

Facing Ali: Facing Ali is a 2009 documentary directed by Pete McCormack about Muhammad Ali (born Cassius Marcellus Clay, Jr. in Louisville, Kentucky) as told from the perspectives of some of the notable opponents he faced during his career: George Chuvalo, Sir Henry Cooper, George Foreman, "Smokin'" Joe Frazier, Larry Holmes (a former sparring partner of Ali), Ron Lyle, Ken Norton, Earnie Shavers, Leon Spinks and Ernie Terrell.

Botherum: Botherum was built for Madison C. Johnson in 1850 or 1851 (sources vary) by John McMurtry, a well-known architect and builder based in Lexington.  The house was intended, in part, as a shrine to Johnson's late wife Sally Ann, a sister of Cassius Marcellus Clay who died giving birth in 1828.

The Soul of a Butterfly: The Soul of a Butterfly is the autobiography of Muhammad Ali, born Cassius Marcellus Clay Jr., a former heavyweight boxer who was a three time World Heavyweight Champion and is the greatest heavyweight of all time.

Odessa Grady Clay: Odessa Lee Clay (née O'Grady; February 12, 1917 – August 20, 1994) was the mother of three-time World Heavyweight Champion Muhammad Ali and Rahman Ali, and the grandmother of Laila Ali.  She married Cassius Marcellus Clay, Sr. in the 1930s and worked for some time as a household domestic to help support her young children.

Supporting paragraphs: Cassius Marcellus Clay Sr. Rahman Ali
Answer: 1943