The principle of Equifinality states that in any closed System the final state is determined by the initial conditions, in Psychology, it refers to how different early experiences in life (examples, parental divorce, physical abuse, parental substance abuse) can lead to similar outcomes (e.g., childhood depression). In other words, there are many different early experiences that can lead to the same psychological disorder.
Other /More definition:
Equifinality refers to the ability of a system to arrive at the same destination from different paths or conditions, the concept that similar outcomes may stem from different early experiences.
Equifinality is likewise, a Developmental psychopathology principle that a behavior or disorder may have several causes.