Son of Beethoven's lifelong friend, Stephan von Breuning, Gerhard first met Beethoven as a child with his father. He was Stephan's son by his father's second marriage.
During Beethoven's final illness, young Gerhard - just entering his teenage years - was a frequent visitor to the Schwarzspanierhaus. His early instincts towards medicine led him to take a particular interest in Beethoven's illness. Beethoven enjoyed his company and nicknamed him "Hosenknopf" [Trouser Button].
Gerhard qualified as a doctor, becoming a highly respected member of the profession. In 1874 he published his personal recollections of Beethoven in "Aus dem Schwarzspanierhaus" - a readable and trustworthy account of Beethoven's last years.