Nisi credideritis non intellegetis

Unless you will have first believed, you will not understand.
We can only go so far on our own.
Faith then brings to completion what reason begins to explore.
Fr Z.

Goes into the carbon dating controversy, the style of sewing done on the linen (only ever seen from 1st Century Masada fabric), and the wounds of the man on the cloth. Definitely blood, as well. DNA evidence, because of the blood degradation could only confirm a human male. No one knows how the image could have been faked. Issue of the age, how it kept so well over time*.

*Holy things tend not to be subject to time in the same way. Our Lady of Guadalupe, for example, was imprinted upon cactus cloth that should have only had a lifespan of 20 years. Instead, it's already survived for 500 years.