At what point do you consider something to be unnatural (as opposed to natural)?

It’s rattling around in my brain and I can’t stop thinking about it.

Where is the line in the sand drawn between natural and unnatural? I’m not asking about whether unnatural things are good or bad, here.

I could write few pages with my thoughts right now, but I’ll just leave some things to consider.

The level of removal from something’s perfectly “natural” state. Trees to paper, for example, would be one level of removal. Tar to ink is another example of one level. If you combined the paper with the ink, that would be two levels of removal.
How many levels removed from a natural state is a car? A computer? A concrete building? Does that level of removal have a factor?

What about intangible things?
Some believe homosexuality is unnatural, because only humans take part in it. Does that mean that in this natural vs. unnatural decision-making, human habits play no role?
No animal (other than us) has religion, so is religion unnatural?
Animals fight one-on-one, but does that mean warfare is natural?

How can you even decide on some of these things?