Overview
- Researchers used a gentle swabbing method on the red chalk drawing known as “Holy Child” and on family correspondence to recover biological material without visible damage.
- Most sequences were non-human, but a subset showed sparse male-specific human signals that the team analyzed for Y‑chromosome markers.
- Some Y markers from the drawing and a cousin’s letter clustered with lineages associated with Tuscany and matched most closely to the broad E1b1/E1b1b grouping.
- The authors caution that mixed, low-quantity DNA, modern handling and conservation, and the lack of authenticated samples from Leonardo prevent any definitive attribution.
- Non-human DNA offered context on materials and setting, including plant traces such as Italian ryegrass, Salix species near the Arno, and Citrus signals uniquely detected on “Holy Child,” and the team calls for replication and stricter contamination controls.