Including Broccoli, all the vegetable of cruciferous family have cancer fighting properites. Specially for this purpose Broccoli is preferred because it has adequate amount of sulforaphane which is a potent compound that boosts the body's enzyme system and as a result of this the cancer causing chemicals can be flushed down easily by the body. Sulforphane also targets the cancer stem cells. These are the cells that promote the tumor growth.
Breeding animals who had desirable or good traits. For example, they bred cows who produced the most milk and plants that produced the most vegetables. :))
