If you have a Base Blueprint with a Event BeginPlay Graph (like a single Print “Parent”) and then extend it. In the newly created Child Blueprint delete just the parent call. The Event BeginPlay keeps transparent and will still execute any logic defined in the parent’s BeginPlay.
If you add custom logic to the child it just works as expected or fully delete Event BeginPlay.
Happened in 4.16. Don’t know if expected behaviour or not - I found it odd.
Can you post prints??
that is really hard to help you with no prints
What? It is a bug report of code still executing even if Parent: BeginPlay is removed.
Thats not a Bug if your node is still transparent its disabled and does nothing. Meaning it wont override the parent implementation. Its there for quick use since its a commonly used Event. If it does not override anything the parents implementation is called. Like the nice comment Bubble indicates 
Nope. It mutates the graph by REMOVING the parent call, still the BeginPlay stays transparent. As said if that is intended behaviour it is fine. But there should not be a difference between removing that ParentCall or adding another call. It both mutates the graph - thus ParentCall should no longer be called.