48 Hours Investigates two stories that reveal much about family, love and determination. The first one is about two women who were mistakenly switched at birth in a small-town Wyoming hospital. They didn't find out until they were in their 40s. Correspondent Erin Moriarty follows these two women as they - and this is really remarkable television - find out about each other and then meet. In the second story, correspondent Susan Spencer tells about a baby who was left under a gazebo in Addison, Ill. in 1972. She's 30 now, and has found her biological mother, thanks to the help of a Web site. Both of these segments are deeply emotional, as you might expect.