The unusual molecules appear to play an important role in cell division. They are most common in rapidly dividing cells, such as cancer cells.
Targeting them could provide a way to halt the cell proliferation at the root of cancer, experts believe.
The discovery marks the 60th anniversary of the historic description of the double helix structure of DNA by James Watson and Francis Crick.
It was made by Cambridge University scientists following in the footsteps of their illustrious predecessors.
In most cases, DNA consists of two strands of linked molecular building blocks called nucleotides entwined around each other. The new research shows "quadruplexes" can also be found within the human genetic code.
The research, published in the journal Nature Chemistry, shows clear links between the molecules and the process of cell division.
Professor Shankar Balasubramanian, whose group carried out the research, said: "We are seeing links between trapping the quadruplexes with molecules and the ability to stop cells dividing.
"The quadruple helix DNA structure may well be the key to new ways of selectively inhibiting the proliferation of cancer cells."