• Question: what are the chances that I was born instead of anyone else?

    Asked by trivorowo to Laura on 26 Jun 2015.
    • Photo: Laura Wales

      Laura Wales answered on 26 Jun 2015:

      This is a great question and actually something I was chatting with my workmates about a few weeks ago. It’s a bizarre thing to think about.

      So, we thought about it in term of what we analyse in the lab. The chance in numbers is dependent on the dad’s sperm count and quality. The lower end of normal is 39 million sperm per ejaculate. When in the reproductive tract, around half of the sperm can swim in the wrong direction. More are lost in the hostile acidic environment. Millions still reach in proximity of the egg where the remaining ones race against each other to use enzymes in the head to “dissolve” the barrier around the egg. The fittest sperm gets through but it can be a close one. Maybe that’s where the saying “you’re one in a million” comes from…..although maybe it should be “one in millionS”.

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