How do you tell the difference between recession and a mature hairline?

This man sent me an email asking this question:

How do you tell the difference between recession and mature hairline?

I asked him to send me a photo of his hairline with his eyebrows lifted high so that the creases show on his forehead. A mature hairline can be seen here because the hairline is about 1/2 inch above the highest crease of the furrowed brow.  The shape of a mature hairline is V-shaped which is a typical male hairline shape.  If you are concerned about a receding hairline, always do this test.