What is Genetics?

Genetics is the study of how traits such as hair color, eye color, and risks for health problems are inherited or passed from parents to their children.

Cancers develop due to changes, called mutations, in genes. Only a small number of cancers are from inherited mutations that are passed down in families. Most cancers are from acquired mutations. Acquired means that the mutations occur in the body after birth.

This can be the result of:

  • Environmental exposures, such as radiation

  • Lifestyle behaviors, such as smoking, eating poorly, or not exercising

  • Chance alone

Acquired changes happen only in the organ or tissue that is affected by cancer. Mutations in a person's DNA build up over time. If mutations affect genes that control cell growth, it may cause a cell to grow out of control. It then becomes a cancer cell.

Therefore, all cancers are genetic. This means that the cancer develops because of a build-up of mutations in genes. But most are not inherited. The number of cancers that comes from a single inherited factor varies depending on the type of tumor. For the more common cancer types, like breast and colon cancer, less than 10% are inherited. The Human Genome Project is an international scientific research project that began in 1990. The project’s goal of mapping the location of all the genes on a cell’s chromosomes was completed in 2003. The analysis of these data will continue for years. It will give scientists the building blocks to determine how diseases, such as cancer, are caused. It will also, hopefully, tell scientists how cancer can be treated and prevented.