A team of scientists at the University of Toronto has discovered, entirely by accident, a groundbreaking mechanism of inheritance that could redefine our understanding of biology.

While investigating cancer signalling pathways in a species of microscopic hermaphroditic worms, the researchers observed something so unexpected that it shifted the entire direction of their research: a trait was being passed down from one generation to the next without any involvement of DNA or RNA.

The discovery began when a peculiar shift in sex determination patterns emerged during the experiment.

Normally, these worms alternate between producing male and female offspring in a balanced, ping-pong-like cycle regulated by two key proteins. However, during the course of the study, the team noticed a disruption in this pattern. The worms began producing more females with each generation, eventually leading to lineages that were entirely female.

Intrigued, the scientists abandoned their original cancer-focused research to investigate this strange occurrence.

What they found was astonishing: the inherited trait was not carried by genetic material in the form of DNA or RNA, but rather through amyloid structures—protein aggregates best known for their role in Alzheimer’s disease.

Amyloids are typically seen as harmful, associated with neurodegenerative disorders. But in this case, the researchers discovered that these structures could store and transmit biological information across generations.

Specifically, they interfered with the regulatory protein cycle that determines sex in the worms. When the “ping-pong” pattern of sex regulation was broken, the worms defaulted to producing only female offspring—and this trait persisted generation after generation.

This form of protein-based inheritance is reminiscent of epigenetics, where gene expression is modified without altering the DNA sequence.

However, the team emphasised that what they discovered is fundamentally different. Epigenetics still depends on DNA, whereas this new mechanism is entirely independent of both DNA and RNA.

The implications are enormous.

If traits can be inherited through proteins alone, it may help explain the mystery of “missing heritability”—traits and diseases that clearly run in families but cannot be fully explained by known genetic factors. Conditions like Type 2 diabetes, certain cancers, Alzheimer’s, Parkinson’s disease, and autism might be influenced by non-genetic inheritance mechanisms we are only beginning to uncover.

Even more intriguing is the fact that amyloid-like structures have already been observed in human oocytes (egg cells), although their role remains unknown.

Could humans also carry inheritable traits through proteins, completely outside the bounds of classical genetics?

While it’s too early to say for sure, this discovery opens the door to a revolutionary new understanding of heredity. As lead researchers from the Derry Lab at the University of Toronto put it, we may be standing at the threshold of a “third form” of inheritance—one that does not rely on nucleic acids, but on protein architecture.

This accidental breakthrough reminds us that science is often driven not just by what we seek, but by what surprises us.