( CNN ) -- Geneticists have begun studying the DNA of Connecticut gunman Adam Lanza , a spokeswoman for the University of Connecticut Health Center said Thursday . The geneticists were asked to join the investigation by the state medical examiner 's office , spokeswoman Carolyn Pennington told CNN . She said there is no specific genetic marker the team is looking for , and that lab results and a complete analysis of the DNA `` are not expected for several weeks ... probably the end of January . '' CNN Chief Medical Correspondent Dr. Sanjay Gupta said it is unlikely investigators will be able to find a genetic clue for what motivated Lanza , who fatally shot 26 people , including 20 children , in the attack on Sandy Hook Elementary School in Newtown , Connecticut on December 14 . Lanza , who had also killed his mother before the school massacre , took his own life with a gunshot to the head . Newtown : No more gifts , please . `` There 's no clear-cut sort of ... genes identified with the types of illnesses , mental illnesses , that may cause this sort of behavior , '' says Gupta . Not only that , Gupta said , but `` there are people who carry these genes who do n't have the behavior still . I think it 's very hard to sort of put those two things together . '' Experts in genetics agree . Although there are genetic components to many mental illnesses , there are hundreds , perhaps thousands , of genes involved . Most believe that no single gene or mutation could be the smoking gun that foretells violent acts like those committed by Lanza . `` There 's nothing you could look at that would give an answer , '' said Steve Warren , chairman of the Department of Human Genetics at Emory University . `` We do n't know a gene that says 'this person has schizophrenia . ' There 's no way to come up with a conclusion that way . '' Opinion : Predicting mass killings impossible . CNN 's Caleb Hellerman contributed to this report .
Spokeswoman : University of Connecticut Health Center geneticists are studying the DNA . Genetics experts say no single gene or mutation will emerge to explain Adam Lanza 's acts . Lanza murdered 26 people , including 20 children , at Sandy Hook school on December 14 .