The structure in a nucleus that holds the hereditary information is the chromosomes.

Here's a breakdown:

* Chromosomes are made up of DNA (deoxyribonucleic acid), which contains the genetic instructions for an organism.

* DNA is organized into long, linear strands called chromatin.

* Chromatin condenses into chromosomes during cell division, making the DNA easier to separate and distribute to daughter cells.

So, chromosomes are essentially bundles of tightly packed DNA that carry the genes responsible for all of our inherited traits.