Children rotating constantly are moving parent with Rigidbody?!

Related to an older question I posted that I haven’t found any answer to…

It seems that having children that are constantly changing their rotation, even if it’s a very small change, will move the root object if it has a Rigidbody that is not kinematic or is not affected by gravity.

Making the rigidbody kinematic stops this, stopping the rotation of the children stops this, removing the rigidbody stops this. Any ideas? Thanks!

It appears that children with non-trigger colliders get aggregated into the parent’s rigidbody. So rotating these children is adding some force to the parent.

So you have a few options:

  1. Add kinematic rigidbodies to the children
  2. Change the child colliders to triggers
  3. Remove the child colliders

Probably a few other options, but having the children with colliders is what is messing it up. Thanks for teaching me something!