I should have been aware of her natural reaction before.

What that natural reaction would have been, was never to be known.

"So what happened today must be seen as a natural reaction on our part."

I know the natural reaction for me is, 'Yeah, what about you?

Putting a hand out to break a fall is a natural reaction.

"Probably a natural reaction to what we went through today."

"It was a natural reaction for what you are now."

It just seemed my natural reaction to run after them.

The natural human reaction to an attack was to move directly toward it.

Anger is also a common and natural reaction to bad news.