Ludwig van Beethoven (1770-1827) was a prodigious composer, credited with 722 works that pushed the boundaries of music and ushered in the Romantic era. Yet, his personal life was marred by several health challenges. Beethoven continued working despite deafness (and what a curse that must have felt like for a composer of his caliber), gastrointestinal troubles, and jaundice. A year ago, scientists sequenced Beethoven’s genome from his hair. They found genetic risk factors for liver disease but nothing conclusive about his other ailments. Now, new research suggests lead toxicity might explain t…