Fraternal or dizygotic twins develop from two different eggs fertilized by separate sperm; they generally share about 50 percent of their genes. Therefore, fraternal twins are essentially like typical ...

The birth of twins in all human populations is puzzling because the female uterus is designed to carry just one fetus. Multiple birth pregnancies have higher frequencies of serious physical and health ...

See more of our trusted coverage when you search. Prefer Newsweek on Google to see more of our trusted coverage when you search. After believing that her daughters were fraternal twins for so long, a ...

Can twins have different fathers? This article explains the science of heteropaternal superfecundation, how hyperovulation works, and the rarity of this biological phenomenon. If those two separate ...

When my baby bump began growing at an alarming rate, I persuaded myself that pregnant women are always bigger the third time around. It was a stretch — literally. At 11 weeks, my belly looked five ...