Some inherited traits bypass the laws of genetics

For over a century, biology has relied on the laws of Gregor Mendel to explain how traits pass from parents to offspring. These rules state that we inherit specific versions of genes, called alleles, which are either dominant or recessive. However, a study of three generations of mice has revealed that roughly seven percent of epigenetic patterns do not follow these classic rules. These chemical tags, which turn genes on or off without changing the DNA sequence, can behave in ways that were previously thought impossible in mammals.