Still, Farey said he's about 40 percent convinced the shroud is authentic and about 60 percent inclined to believe it is a forgery.
"There is a pretty substantial amount of evidence on both sides," Farey said.
The oldest DNA snippets (which tend to be shorter because DNA breaks down over time) are found in many places on the shroud, and come from genetic lineages typically found only in India, Barcaccia said.
That finding suggests that the shroud was manufactured in India before somehow making its way to Europe, as Indians had little contact with Europeans at the time of its origin.
The team also sequenced the human mitochondrial DNA (DNA passed from mother to child) found in dust from the shroud.
The genetic lineage, or haplotype, of the DNA snippets suggested that people ranging from North African Berbers to East Africans to inhabitants of China touched the garment.
"So the proper thing to do is to maintain an open mind at the moment." However, using DNA analysis and more sophisticated scientific techniques could ultimately settle the question, Farey said.
For instance, geologists can now determine the origin of rock with incredible precision, by analyzing its ratio of isotopes of certain elements.
"Also, the sub-genus level of taxon that has been reached is not near enough to the species level that is needed to determine the area of origin for each plant." The researchers also mistakenly relied on an interpretative method that is used to analyze thousands of grains of pollen in a lake, she said.
In that environment, the conditions that led to the deposition of pollen — rain and wind, for instance — are known.
"In my opinion, it is hard to believe that in the past centuries, in a historical interval spanning the medieval period, different subjects — such as priests, monks or nuns, as well [as] devotees and other subjects of Indian ancestry — have had the possibility to come in contact with the shroud in France and/or Turin," Barcaccia said.
Unsettled question But the new results don't settle questions about the shroud's authenticity, said Hugh Farey, editor of the British Society of the Turin Shroud newsletter. ] As far as the plant DNA goes, "they've done a good job, and they've identified a number of species that mean, broadly speaking, nothing at all," Farey told Live Science.
A new analysis of DNA from the Shroud of Turin reveals that people from all over the world have touched the venerated garment.