Here's why:

* Nucleotides: These are the building blocks of DNA. Each nucleotide has a sugar, a phosphate group, and a nitrogenous base. There are four different nitrogenous bases: adenine (A), thymine (T), guanine (G), and cytosine (C).

* Sequence: The specific order of these bases along the DNA molecule is called the sequence. This sequence is like a code that dictates the production of proteins.

* Proteins: Proteins are the workhorses of the cell, carrying out a wide variety of functions that determine our traits.

* Gene Expression: The DNA sequence of a gene determines the amino acid sequence of the protein it codes for. This process, called gene expression, is how DNA ultimately controls traits.

In summary: The sequence of nucleotides in DNA provides the instructions for building proteins, which in turn determine our physical characteristics and other traits.