Is mirroring someone's body language as form of flirting or attraction reliable?

I'm asking this because for whatever reason this particular girl was sitting opposite me in group study and from time to time I would notice that either she was sitting the exact way that I was or I was sub consciously was sitting the way she was. It was kind of weird, but in a good way.

What are your views?
Yes
No
It depends (explanations please)
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Is mirroring someone's body language as form of flirting or attraction reliable?
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