I sat next to a mum and a three year old yesterday on a flight and the child kept undoing her seat belt and standing up on the seat both on take off and approach. A sweet little girl but the mother didn't seem in the least concerned about the possible risk to the child or other passengers, nor did she attempt to support the cabin crew in doing their job. In the end I tightened the belt round the child and fastened it with the metal flap on the inside so she couldn't release it. Problem solved, not very elegantly, but solved.
Then when I was helping the mother to get her bag out of the overhead, a woman tried to force her way past everybody rudely, cursing and swearing at me when I suggested she learned some manners and patience. I sometimes wonder what happens to people when they get on an aircraft.