The key (no pun intended) is the 1K blend. That value is automatically added to a parented object and represents the parenting weight... a blend value of 1 means that the parent weight applies in full. A value of 0 means the value is broken. I don't know precicely how the above were generated as I'm only just learning about breaking parenting, but the blend value is where to start.

You can even change individual weights if you've parented an object to multiple targets, but that's in a different node and not an answer to your question