We all know that we share physical similarities with our siblings, our parents or even our grandparents. And you’ve probably heard the phrase ‘it’s in your genes’. But what does that really mean?

Often described as the basic units of heredity, genes are responsible for passing traits from your parents to you, and you to your own children. The colour of your hair or eyes. Your blood type. Even your likelihood of developing certain diseases or health conditions. They’re all dictated by genes.

What do genes do?

In basic terms, genes are instructions. Just like a great chef writes down their best recipes so that they can keep producing them for years to come, your genes tell your cells how to create (and keep creating) specific proteins like pigment, enzymes or haemoglobin.

What are genes made of?

Genes are actually segments of a very complex code called DNA – a code that contains all the information needed to keep you functioning properly.

Incredibly, there’s so much DNA in a single human that if you were to lay it out end to end, it would stretch to the moon and back – 1,500 times. So the only way your cells can store it is to compact it into tightly wound strands, otherwise known as chromosomes.

How many chromosomes do I have?

In each of your cells, there are 46 chromosomes that you inherited in equal parts from your father and mother (22 pairs of autosomes and a pair of sex chromosomes) – all containing the genetic information essential to making you you.