Couples were offered the chance to see if they will produce redhead children. The DNA test, first available at the 2013 “Who Do You Think You Are?” exhibition in London, shows the depth of ancestry that can be read from a simple saliva swab.

Even if neither person has red hair they may still carry the “ginger gene.”

Doctor Jim Wilson, chief scientist at BritainsDNA told the Daily Mail, “Through a simple saliva test to determine deep ancestry, we can also identify whether an individual is a carrier of any of the three common redhead variants in the gene MC1R.

“This means that families can carry a variant for generations, and when one carrier has children with another carrier, a red-headed baby can appear seemingly out of nowhere.”

Four in ten people carry the redhead gene, without having red hair themselves. About 40 percent of men and women in Ireland have the redhead gene and ten percent have red hair.

In Scotland just 30 percent carry the gene and 13 percent of people have red hair, while in England only six percent of people have red hair.

Finding the silent “ginger gene” is not only beneficial to finding out if your offspring will have red hair but it is also means that those carrying the gene are exposed to a range of increased health risks such as increased sensitivity to pain, skin cancer, Parkinson’s disease and Tourettes.

* Originally published in 2013.