In 1802, a despairing Beethoven wrote a letter asking that after his death, doctors describe his illness to the world so people would understand what he had endured. In 2023, scientists sequenced his genome from five locks of his hair and answered him — 196 years late, and not with the answers anyone expected

In October 1802, in a small village outside Vienna called Heiligenstadt, Ludwig van Beethoven sat down to write a letter to his brothers. “So that so far as possible at least the world may become reconciled with me after my death,” he wrote. He also kept the Heiligenstadt letter in a hidden compartment of his writing desk, unopened and unread by anyone else. What the DNA could not answerThe specific question Beethoven had actually wanted answered — the cause of his deafness — remained open. What it produced, in the end, was a specific and imperfect answer to a request Beethoven had made 196 years earlier.