JOEL - Your father-in-law's information is not exactly correct. We do not know for sure exactly where the Garden of Eden was located. Joseph Smith and others believed that it was in or near Jackson County Missouri, and that Adam dwelt near there after He was cast out of the Garden. But where he actually dwelt may have been far removed from the Garden of Eden. Also, at the time Adam lived there all the land was together in one spot on the earth (See Pangaea). The Tigris/Euphrates river area may have been close enough to the area now called Missouri to be accessible to Adam. Later the lands separated in the days of Peleg(Gen. 10:25).

Another thing to consider is that many christians and scholars today assume that the original garden was located somewhere in the Mesopotamian region (around present day Iraq) where the modern Tigris and Euphrates rivers flow. However, the Bible records a devastating worldwide Flood, many centuries after Adam and Eve were expelled from the Garden. The flood covered the entire earth, including those rivers. After the flood sedimentary layers sometimes miles thick may have buried forever the pre-Flood world, including the original Tigris and Euphrates rivers. Therefore, today's Tigris and Euphrates may have been named after the original pre-Flood rivers but may not be in the same place.