Okay, please change your manual render setting to 'Cast Shadows' and 'Raytracing'  to on.  You have raytracing activated in your infinite light but you are not taking advantage of the feature in your render settings. 

I have a very strong suspicion that the skin texture shaders are completely off, and are casting either a grayish or bluish tint.  The same problem exists with V4 and M4's basic skin textures.  Follow Laurie's recommendation about the VSSProp which contains a builtin skin shader template.  However, there is a slight learning curve, so will probably come back with more questions about it's implementation.  Try to read about VSS as much as you can understand.  I guarantee that using VSS is far more superior than using the character's default shaders.