Despite the active development of medicine, scientists still know very little about the nature of many processes in the human body. For example, from a school biology course, we know that an embryo becomes a girl due to a pair of X chromosomes in its genome. If one of them is Y, then we get a boy. However, researchers are still unaware of the processes that drive this. In a recent study of “junk” DNA, genetics obtained a rather interesting result. Without exerting any influence on the sex chromosomes, they successfully changed the floor of the laboratory mouse. The opening belongs to a team from the London Francis Crick Institute, led by Robin Lowell-Badge. Its results have already been published in scientific journals. As scientists have established, a couple of genes are responsible for starting the sexual development program: Sry and Sox9. Starting the first is possible only after the complete formation of the sex of the embryo. The second produces the genitals from the blanks of the reproductive cells. Surprisingly, Sry damage turns female fetuses into males. Studying the problem further, experts have identified a piece of junk DNA near the Sox9 gene, which was named Enh13. It forces cellular proteins to decrypt a portion of the chromosome that contains Sox9. Due to this, its activity increases. A male embryo development program is included. As an experiment, two mice were crossed by experts. One had a working Enh13, the other a damaged one. When the embryos developed, some were males and some were females. The researchers then deactivated the remaining active Enh13 gene. As a result, males lost their male genital organs and “grown” female ones. In this case, exclusively female mice were born, although during pregnancy the alignment was different. Researchers have deduced from this that disruptions in mammals in sexual development can be caused by mutations in the genes above and in junk DNA. Since sexual deviations do not always occur against the background of damage to germ cells.