Add an offset distance between 2 spawned objects

I am trying to make a simple 2d platformer game in unity. While doing it i have encountered a problem with spawning objects. The newly spawned objects is overlapping each other. My question is how to add an offset distance between the gameobjects. Below is the code i used for the spawning.

 public class spawnscript : MonoBehaviour {
    public GameObject[] obj;
    public float spawnMin;
    public float spawnMax;

    // Use this for initialization
    void Start () {
        Spawn ();
    }

    void Spawn()
    {
        Instantiate (obj [Random.Range (0, obj.GetLength (0))], transform.position, Quaternion.identity);
        Invoke ("Spawn", Random.Range (spawnMin, spawnMax));
    }
}

the game objects is having different dimensions

Create a new Vector3 variable, call it offset and add it to the transform.position.