response: When each twin is fertilized by its own sperm cell, it is called fraternal.
original_response: When each twin is fertilized by its own sperm cell, it is called fraternal
history: I have a twin in real life and when people see us together, I get real sick of them asking if we are twins! How interesting! A developing fetus is called a singleton if they are alone but a multiple if there is more than one developing! Those embryos sure like multiplying! I wonder if twins are more rarer than triplets? I don't actually know, though the twin rate rose 76% between 1980 and 2009, ending up at 33.3 for every 1,000 births. Wow, do you know what caused the spike in the rate? Is it a genetic thing? I'm not sure, but the Yoruba people have the highest twin rate in the world, possibly because they eat a yam that contains a natural phytoestrogen. Lol, you can eat a fruit that increases the chance of getting twins. That is funny. I heard there is different types of twins too like identical and I forgot the name of the other one?
knowledge: In fraternal twins, each twin is fertilized by its own sperm cell.