Hand over a handful of Eucharists...I know of a lab near me where they can be tested for DNA...
They retain the appearance of bread. That appearance would include chemical composition. They don't have DNA.
I thought we all knew that.
The Church doesn't claim that the bread turns into Christ's physical flesh.
Transubstantiation means "change in substance." The terms derive from Aristotelian/Scholastic philosophy, meaning the quiddity or "whatness" of a thing changes, while the substance's appearance or "accidents" change.
Regardless, common opinion is that the substance of the host is changed into Christ's glorified body.
Nevertheless, there is an 8th century miracle where the host transformed into human flesh in the hands of a skeptical priest. Scientific testing has shown it to be the flesh of a human heart.
•The Flesh is real Flesh. The Blood is real Blood.•The Flesh and the Blood belong to the human species.
•The Flesh consists of the muscular tissue of the heart.
•In the Flesh we see present in section: the myocardium, the endocardium, the vagus nerve and also the left ventricle of the heart for the large thickness of the myocardium.
•The Flesh is a "HEART" complete in its essential structure.
•The Flesh and the Blood have the same blood-type: AB (Blood-type identical to that which Prof. Baima Bollone uncovered in the Holy Shroud of Turin).
•In the Blood there were found proteins in the same normal proportions (percentage-wise) as are found in the sero-proteic make-up of the fresh normal blood.
•In the Blood there were also found these minerals: chlorides, phosphorus, magnesium, potassium, sodium and calcium.
•The preservation of the Flesh and of the Blood, which were left in their natural state for twelve centuries and exposed to the action of atmospheric and biological agents, remains an extraordinary phenomenon.