When crime scene investigators go after criminals, it’s usually a time-consuming, multi-step process that involves finding out who the criminal is, what they look like and where they are. How much faster would the process be if it was possible to determine someone’s appearance with just their DNA?
In a technique known as phenotyping, scientists are able to determine the physical appearance of an individual based solely on their DNA.
A phenotype refers to the physical characteristics of an individual from both environmental and genetic factors while a genotype refers to the DNA sequences that produce these phenotypes. DNA phenotyping is a technique used by forensic scientists to predict an individual’s phenotype given their genotype.
Whether at a crime scene or for research, DNA can be collected to study the genes unique to whoever the sample came from. Eye color, skin color, ethnicity, hair color, nose shape, etc. are all characteristics that can be derived from a small sample of DNA.
The DNA collected is processed through programs with algorithms to produce a predictive profile of the individual.
In a 2015 study published in PLOS Genetics, Mark Shriver, researcher at Penn State University, compiled a list of genetic mutations that produced unique facial features such as a widow’s peak, freckles, lip size, nose shape and eye shape.
These markers were then inserted into a program to generate a predictive algorithm to help build a predictive physical appearance of an individual.
Some traits, such as eye color and skin pigmentation, were easily predictable using genes while, according to Shriver, others were not.
“[F]eatures such as the strength of the brow ridge, the spacing between the eyes... are largely scientifically unexplained,” Shriver said, according to the International Science Times.
With more than 24,000 genes contributing to the overall physical characteristics of an individual, narrowing down one phenotype to a certain gene becomes very difficult.
Despite the difficulties associated with it, DNA phenotyping has proved to be a valuable technique in the world of criminal investigation. Not only does it have the potential to help with identifying criminals, but it also has already been used to help identify unidentifiable victims.
Early in 2015, a hand washed up on a coastline in Brooklyn, N.Y., followed shortly after by other body parts including a foot and a rib cage. Brooklyn detectives, led by Patrick Conry at the time, used DNA phenotyping to help predict the victim’s facial appearance.
“Once we identify the deceased, it’d go a long way to solving the crime itself,” Conry said, according to The New York Times.
This is just one example of when criminal investigators have delved into DNA phenotyping to help with an unsolved case. DNA phenotyping is primarily used to identify victims; however, its potential use in identifying criminals continues to be explored.
DNA phenotyping, although innovative, is still at the infancy stage. It produces a generic face that matches all of the traits present in the DNA, which could lead to false accusations.
“The problem is, its use will place actual people, innocent of wrongdoing, under criminal suspicion without any basis in fact or science,” Robert Perry, the legislative director of the New York Civil Liberties Union, said, according to The New York Times.
In addition to dangers of false accusations, DNA phenotyping doesn’t account for environmental factors that influence one’s appearance — such as smoking and injuries. There is room for improvement when it comes to using phenotyping as a criminal tool.
Further research is being done to continue refining DNA phenotyping to sharpen the accuracy of its predictions.
