I believe Bamber was saying he hated his parents recently before the massacre
It's alright a 9 year old saying it, while sulking after a telling off. But a 24 year old man.
Children may not get on with their parents, and contact may become minimal once the child has grown up. However Bamber had to work for his parents and engage with Neville on a daily basis. It was Neville's farm so he would have told Bamber what to do. Despite working on WHF he told MM he had not spoken to June for years.