There was a 15 year study done in France with some 350 women between the ages of 18-35. They had half of the women stop wearing bras completely and the other half go on about as usual. The group that stopped wearing bras actually had their boobs get perkier and their nipples raise about .3 inches (almost half an inch!). This is because the ones who wore bras didn't build deep tissue. Their body didn't see a need for it since they were being held up all the time. The women who stopped wearing bras not only built deep tissue, but had a boost in collagen production and elasticity.