Who is responsible if a 12 year old is baby sitting a younger sibling and something happens where the younger child gets hurt or injured?

In most cases, the responsibility for a younger child's injury while being babysat by a 12-year-old typically falls on the parents or guardians of both the babysitter and the injured child. The parents are expected to ensure that the babysitter is capable and responsible enough to care for a younger child. However, if negligence can be proven on the part of the babysitter, they may also share some liability. Ultimately, the specifics can depend on local laws and the circumstances surrounding the incident.