Neutrons’ ‘evil twins’ may be crushing stars into black holes

The universe may be filled with “mirror” particles — and these otherwise-undetectable particles could be shrinking the densest stars in the universe, turning them into black holes, a new study suggests.  These hypothetical evil twins of ordinary particles would experience a flipped version of the laws of physics, as if the rules that govern known […]

Identical twins don’t share 100% of their DNA

Identical twins form from the same egg and get the same genetic material from their parents — but that doesn’t mean they’re genetically identical by the time they’re born. That’s because so-called identical twins pick up genetic mutations in the womb, as their cells weave new strands of DNA and then split into more and […]

Some identical twins don’t have identical DNA

twin girls

Identical twins may not be carbon copies at the DNA level after all. On average, identical twins differ by 5.2 genetic changes, researchers report January 7 in Nature Genetics. The finding is important because identical twins — also called monozygotic twins because they come from a single fertilized egg — are often studied to determine […]

31,000-year-old burial holds world’s oldest known identical twins

An ancient grave in Austria may represent the oldest burial of twins on record, a new study finds. The 31,000-year-old burial dates to the Upper Paleolithic (a period lasting from 40,000 to 10,000 years ago), also known as the Old Stone Age. One of the infants died shortly after childbirth, while his twin brother lived […]