Unity detecting collision without touching

I have an object that parents an object whenever it collides with it (using OnCollisionEnter). However there can be some significant distance between the two colliders. Is there anyway to fix it so it collides when the colliders touch? Here is the relevant code.

   void OnCollisionEnter(Collision collision)
        Collider otherObject = collision.gameObject.GetComponent<Collider>();

            otherObject.gameObject.transform.parent = gameObject.transform;
            otherObject.enabled = false;

The significant distant you are talking about must not really a distant because collision is made on the basis of colliders and not renderers. .
Are you sure your 3d objects colliders are exactly of the same size of the model ?