"This article examines the "scuttling" gangs of late Victorian Manchester and Salford, drawing upon a sample of 250 gang-related crimes of violence reported in the local press between 1870 and 1900. Over 90 per cent of those charged in these cases were working-class males aged between fourteen and nineteen. Affrays between rival neighbourhood-based gangs, which were characterized by the widespread use of knives, were not confined to the most notorious "slum" districts but spanned the working-class districts of the Manchester conurbation. Gang conflicts do not appear to have been structured to any sign)ficant extent by either short-term economic trends or ethnic tensions. Gang violence was rooted in working-class codes of toughness and manliness and allowed young men on the brink of adulthood to act out the established role of the "hard" man and thus to acquire considerable kudos and peer-group recognition."
Plus ca change...
Two major factors here. First thing is that kids are incapable of considering consequences for other people. That's physically incapable - the part of their mental setup which lets them put themselves in someone else's shoes is literally not present. The other part is that peer pressure is more central to kids' experiences than any adult instructions. Kids have always behaved badly, and it will continue to happen for as long as human physical development works the way it does.
This doesn't excuse their father's attitude though. Kids can't learn that there's consequences to their actions for other people unless they're forced to examine those actions.