Researchers from Stanford University have revealed more information about a particular genetic variation in humans responsible for blonde hair. A single-letter change is enough in the genetic code to have blonde hair.

Lead researcher David Kingsley pointed out that the genetic variation of which they are talking about is associated with blonde hair and not with eye colour or any other pigmentation traits.

Kingsley shared he has studied the three-spined stickleback for more than 10 years. He carried out research on how the fish adapted around the world. Kingsley figured out the molecular changes that lead to evolution.

Experiment on mice was carried that unveiled blonde switch turned new born mice with light, golden-brown fur. The switch brings changes in the activity of a gene called 'Kit Ligand'. The activity reduced Kit Ligand activity by around 20%.

"The genetic mechanism that controls blonde hair doesn't alter the biology of any other part of the body. It's a good example of a trait that's skin deep - and only skin deep", affirmed researchers.

The gene was also found to be involved in the development of pigment-producing cells. It also influences the behaviour of blood stem cells, gut neurons and sperm or egg precursors. Seeing so many functions being performed by the gene, Kingsley said it seems the genome is filled with switches.

Kingsley said in future many more such researches would be carried out that will further increase the understanding of the molecular basis of human diversity as well the susceptibility of many common diseases.