Cloned objects choosing different colors

I have a game were a grid will spawn and i need the colors of each cube on the grid to randomize but everyone of them is a clone, currently when i press start simulation the cubes will go on flashing or will be all white or black (occasionally they will be half and half like their supposed to) what am i doing wrong?

code:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using System;

public class Wall : MonoBehaviour {
    //get random
    System.Random rdn;
    //clone temp random
    private int _tempRnd;
    //textures
    public Texture2D White;
    public Texture2D Black;

    void Start () {
        //pick random and then input into clone temp random
        rdn = new System.Random();
        _tempRnd = rdn.Next(1, 3);
        // send log for viewing
        Debug.Log(_tempRnd);
        //pick the number anc choose 
        if (_tempRnd == 1) 
        {
            GetComponent<Renderer>().material.mainTexture = White;
        }
        else
        {
            GetComponent<Renderer>().material.mainTexture = Black;
        }
	}
}

This is just a theory, but I think the problem is that you are using a separate System.Random object in each instance of the Wall script and get their Start() method called on the same frame. That way System.Random objects get initialized with the same seed, so rdn.Next() will return the same value for all. When it is half-half, some of the Wall scripts get their Start() called on a different frame.

To solve this, either use Unity’s built-in randomizer ( UnityEngine.Random) or make rdn static and only assign it the first time, when it is null. If you don’t have a special reason to use System.Random, then just go with UnityEngine.Random, like this:

// don't need to instantiate UnityEngine's Random
_tempRnd = Random.Range(1, 3); // will return 1 or 2
// the rest is the same; although now you don't need rdn variable