I have a some game objects that are a unit away from the center. They are all contained in a parent object, see the image below.

When I rotate the parent object by 60°, the game objects individually rotate, as below.

Below is the script attached to the parent object that I use to rotate the parent object.

    IEnumerator RotateSquaresParent(Vector3 byAngles, float duration)
{
    Quaternion fromAngle = gameObject.transform.rotation ;
    Quaternion toAngle = Quaternion.Euler (transform.eulerAngles);
    toAngle = Quaternion.Euler (gameObject.transform.eulerAngles - byAngles);

    for(float t = 0f ; t <= 1f ; t += Time.deltaTime/duration)
    {
        gameObject.transform.rotation = Quaternion.Lerp(fromAngle, toAngle, t) ;
        yield return null ;

    }
    gameObject.transform.rotation = Quaternion.Lerp(fromAngle, toAngle, 1);

}

How can I rotate the parent object containing these square game objects without rotating them individually?