For a GameObjectwith a Renderer component, calling renderer.bounds.center will return the center point of that game object.

However, I have a root GameObjectthat just serves as the parent Transform of many other GameObjects:

+ Parent without renderer
    - Child model
    - Child model
    - Child model

How can I retrieve the center of this parent object GameObject as a whole (including its children)?

You want to average just the max and min in each direction, So something like P: (Max(x1, x2, x3) + Min(x1, x2, x3))/2; (Max(y1, y2, y3) + Min(y1, y2, y3))/2; (Max(z1, z2, z3) + Min(z1, z2, z3))/2; ,

You should try to average the children’s center coordinates

P: ( (x1+x2+x3)/3; (y1+y2+y3)/3; (z1+z2+z3)/3)