What became fathers new habit in the book a child called it?

The father in "A Child Called 'It'" did not develop a new habit. He continued his abusive behavior throughout the book.

While David Pelzer, the author, mentions his father's habit of drinking, this is not presented as a new habit but as a constant aspect of his personality, exacerbating his violence and cruelty.

The book focuses on the relentless abuse David endured at the hands of his father, not on any potential changes in his behavior.