rigidbody.AddForce affects all clones

Hello, on scene I have 3 balls with Ball.cs script attached to each of them. And when I push ball with mouse all balls start moving, but I need that only one that I touch moves.

Here is my FixedUpdate:

void FixedUpdate() {
    if(!isMoving) {
    	if (Input.GetMouseButtonDown (0)) {
    	    Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
    	    RaycastHit hit;
    	    if (Physics.Raycast(ray, out hit, 100)) {
    		if(hit.collider.tag == "Ball") {
    		    startPos = hit.point;
    	if (startPos != Vector3.zero && Input.GetMouseButtonUp(0)) {
    	    endPos = Camera.main.ScreenToWorldPoint(Input.mousePosition);
    	    Vector3 direction = endPos - startPos;
    	    float distance = Vector3.Distance(endPos, startPos);
    	    rigidbody.AddForce(direction * distance * force * Time.deltaTime, ForceMode.Impulse);
    	    isMoving = true;
    } else {
    	if(rigidbody.velocity.sqrMagnitude == 0) {
    	    isMoving = false;
    	    startPos = endPos = Vector3.zero;

You are not checking which ball gets hit. You just have a check in all the balls that if a click is made and a object with the Ball tag is hit, the object running the script gets affected. All the balls run the script and IF a click hits a ball, all balls get affected.

On top of checking the hit.collider.tag matches, check also that the gameobject of the hit is the same as this.gameObject.