You said you base your idea of the thing being a gray on your wife seeing a shadow with the typical skinny 'alien' body shape. I just wanted to
suggest that you can't draw conclusions from that incident because a normal person's shadow can take on that shape if the light behind the person is
at the right intensity and angle. Also, since 'it' uses a shield of some kind to avoid being seen, the weird shadow could be attributed to how the
shield bends light.