Defaut replication setting in ACharacter

For a child class of ACharacter,when I call detach() or attach() functions on its SkeletonMeshComponent,it will replicate to the client automaticlly, but I never set bIsReplicated = true.

I have dive into the source code of SkeletonMeshComponent, but I can not find any specific setting such as bIsReplicated = true in SkeletonMeshComponent neither parent class SceneComponent.

What happend behind and how?