Isotope analysis
A recent development in forensic science is the isotopic analysis of hair strands. Hair has a recognisable growth rate of 9-11mm per month or 15 cm per year. Human hair growth is primarily a function of diet, especially drinking water intake. The stable isotopic ratios of drinking water are a function of location, and the geology that the water percolates through. Sr, Sr and oxygen isotope variations are different all over the world. These differences in isotopic ratio are then biologically 'set' in our hair as it grows and it has therefore become possible to identify recent geographic histories by the analysis of hair strands. For example, it could be possible to identify whether a terrorist suspect had recently been to a particular location from hair analysis. This hair analysis is a non-invasive method which is becoming very popular in cases that DNA or other traditional means are bringing no answers.
Melanocortin 1 receptor
In the United States, about 25% of the population carries the mutated melanocortin 1 receptor that causes red hair. With one in four people as carriers, the chance of two people having a child with red hair is about 2% (one in 64). The prevalence of red hair varies considerably worldwide. People with freckles and no red hair have an 85% chance of carrying the "MC1R" gene that is connected to red hair. People with no freckles and no red hair have an 18% chance of carrying the "MC1R" gene linked to red hair. Eight genes have been identified in humans that control whether the MC1R gene is turned on and the person has red hair.