Thomas Jefferson and Sally Hemings (the slave he had an affair with) were thirty years apart in age (he older than her). I've asked a few history-loving friends and they told me that even if Jefferson had married someone the same age as Hemings (thirty years younger than him), it wouldn't have been frowned upon at all because 60-70 year old men commonly took teenage or 20-some-year-old wives. Now, however, most people would consider this behavior disgusting and try to help the girl. When did this shift happen and how?