The segments of DNA (deoxyribonucleic acid) that control what a child inherits are the genes.
Genes are responsible for a plethora of things, including more noticeable things like your hair color, but also less noticeable things like the way your ear-lobes attach. According to the Human Genome Project, humans have approximately <em>25,000 </em>genes. While most of these are the same among average people, there are still hundreds that are different, and make you- <em>you</em>!
Each parent provides a set of genes, which the child inherits. This controls almost all aspects of the child's life, including their appearance, the way they think, and even disabilities or gifts. In short, genes, which you inherit from your parents, control everything about you, from your hair color to your ability to learn.