Possibly not great for any artists maintaining anonymity/pseudo anonymity but... https://en.wikipedia.org/wiki/Body_fluids_in_art https://en.wikipedia.org/wiki

Possibly not great for any artists maintaining anonymity/pseudo anonymity but... https://en.wikipedia.org/wiki/Body_fluids_in_art https://en.wikipedia.org/wiki/Body_fluids_in_art Semen, due to the ability to sequence the DNA and difficulty obtaining a sample, is a fine genetic watermark.