To understand how our brains develop, we need to understand a bit about how genetic information is used to build them. So, let’s bring back Matt, our resident genetics expert. So, Matt, how does your body know how to build you?>>Virtually, every cell in your body, including your brain cells has all the information necessary to build you. Inside every cell resides the genetic construction or DNA that is arranged in 23 pairs of chromosomes.>>Wait, so I know that DNA is the blueprint for making a living thing, but what role do chromosomes play?>>chromosomes are actually long strands of DNA wrapped around proteins. You’ve probably seen pictures of them before. It’s how our cells organize this information structurally.>>so, that’s cool, but how does it translate into who I am, or who you are?>>Well, DNA is made up of four building blocks, called nucleotides. Adenine, Thymine, Guanine, and Cytosine. We usually refer to just the letters. A, T, G and C. You have over 3 billion of these letters in a unique sequence that makes up who you are. And your cells use this as a set of instructions to create you.>>Wow, 3 billion sounds like a lot. I wonder how that compares to other living organisms?