  Recently it has been found that different physical systems driven by
identical random noise behave exactly identical after a long time. It is also
suggested that this is an outcome of finite precision in numerical experiments.
Here we show that the origin of the non-chaotic behavior lies in the structural
instability of the attractor of these systems which changes to a stable fixed
point for strong enough drive. We see this to be true in all the systems
studied in literature. Thus we affirm that in chaotic systems, synchronization
can not occur only by addition of noise unless the noise destroys the strange
attractor and the system is no longer chaotic.
