Dr. Michael Cox, a biochemistry professor at the University of Wisconsin, told Unsolved that the scientists found examples where the genes only repeated between 10 and 30 times in the human population. Chromosome seven is one of the spots where those repeats occur.
“You inherit these alleles from your father and mother,” Cox said. “So you get one from dad and one from mom. So on chromosome seven at this one locus … you might get a repeat that repeats 12 times (from your mom). And from your dad, you get another chromosome seven and you might get one that repeats 17 times.”