As a young 12 year old boy, Diokno would go with his father to trials in the provinces. He would carry his father’s bag, and sit on a small chair reserved for him behind the counsel’s table. He learned English through a private tutor during the American Commonwealth period. Growing up, Diokno relished having Spanish dishes at home, namely "tapas" or side dishes such as "angulas", "white embutido", "galantina", and "chorizos". He liked Filipino food as well and enjoyed rice mixed with "gatas ng kalabaw" (carabao’s milk), raw eggs, and "tapang usa" (cured venison).