The Push-up Bra has its origins in the 15th and 16th centuries, when prominent breasts came into style. Women's corsets literally "pushed up" the breasts to emphasis roundness and fullness. An emphasis that is still very popular today.
To give you a brief history, the first bra patent was submitted in 1914 by Mary Phelps Jacobs who hated her corset. Yet, it wasn't until the 1960s that Canadian inventor Louise Poirier introduced the Wonderbra. And viola -- comfort and cleavage.
The Wonderbra has inspired many imitations and gathered many more followers of both sexes. No wonder it's considered the 5th greatest Canadian invention of its time.