From Aberforth, Harry, Ron,and Hermione learned Dumbledore's father had what?

From the text:

His attention caught, Harry examined the picture more carefully. Dumbledore’s father, Percival, was a good-looking man with eyes that seemed to twinkle even in this faded old photograph.

For his part, Albus had arrived at Hogwarts under the burden of unwanted notoriety. Scarcely a year previously, his father, Percival, had been convicted of a savage and well-publicized attack upon three young Muggles.