A new life begins when a mature egg from a woman is fertilized by a sperm from a man. The egg and sperm each contain a single copy of each gene in the human genome—half the amount necessary for life. Together, the two unite to form a complete set of genes containing all the DNA necessary to make a new human being.


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J&J Vaccine and Blood Clots: What to Know If You Already Got the Shot

Six cases of cerebral venous sinus thrombosis have been reported among the 6.8 million people who received the J&J vaccine.

After the Johnson & Johnson vaccine was associated with cases of "rare and severe" blood clots, the U.S. government recommended officials pause giving the shot. But nearly 7 million people have already received the vaccine. So the news has a lot of people wondering if they should be concerned and what they need to look for.

The short answer: "Don't panic."

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