Explain · Like I'm five version
DNA in terms of Marbles
Did you know that your body is full of tiny, colourful marbles that tell you how to grow?
Inside every single piece of your body, there is a long, twisty string of marbles. These marbles come in four special colours, and they are always stuck together in pairs. The order of these coloured marbles is like a secret code. This code is your very own recipe, and it tells your body exactly what to do. It decides if you will have curly hair, blue eyes, or even how tall you might grow to be one day.
When you grow, your body needs to make brand new cells. To do this, your body pulls the string of marbles apart right down the middle, like unzipping a zip. Then, it finds new, matching marbles to fit into the empty spaces on each side. Soon, you have two perfect strings of marbles where there was only one before. It is just like copying your favourite Lego instructions, but much, much smaller and hidden deep inside you.
Every person on Earth has a string of marbles that is a little bit different, which is why we all look like ourselves. You got half of your marble string from your mum, and half from your dad. That is why you might have your dad's nose or your mum's smile. It is a wonderful mix that makes you special, one little marble at a time.
Where the analogy breaks downReal marbles are solid and do not contain chemical instructions for building a human.
Cepheus