Country legend Willie Nelson began smoking marijuana at just 10 years old, according to an explosive new biography. Joe Nick Patoski's Willie Nelson: An Epic Life reveals all about the 74-year-old father-of-seven's hellraising life, including details of his infamous drug use and four marriages. Patoski claims that Nelson first smoked pot as a 10-year-old, that he battled other drug addictions as well as alcoholism. A publishing source tells U.S. tabloid, "His constant use of various substances and booze made for chaos during his love affairs and... marriages." But, according to biographer Patoski, one lover, a Cherokee girl, attempted to tame Willie's cheating ways with a broom. The source explains, "She'd beat him with a broom." The book also reveals Nelson was threatened with a gun by his second wife Shirley Collie when she discovered him cheating with his future spouse Connie Koepke. The book also documents the time Nelson smoked pot on the White House roof while staying in Washington D.C. as the guest of then-U.S. President Jimmy Carter. Nelson recently revealed how he's cut back on his marijuana intake and increased his running regimen in a bid to prolong his life.