Jumping genes, more formally known as transposons or transposable elements, are DNA segments with the blueprints for proteins that help to either copy the segment or remove it, then insert it into a new place in the genome. Human genomes are littered with the remnants of ancient jumping genes, but because cells have an interest in limiting such trespasses, they have evolved ways to regulate them. Most jumping genes have mutated and can no longer move, but these “rusting hulks” are still passed down from generation to generation.
One exception is a jumping gene called L1, which has been so successful that copies of it make up about 20 percent of human DNA. While many of these copies are now mutated and dormant, others are still active and thus the subject of much interest from geneticists.
Read more at: Phys.org