Robbing the Cradle

I've been indexing the 1900 Jefferson County, Mississippi today for FamilySearchIndexing.org. I have to say that I found some rather interesting data on the census. My first shocker was finding a 21-year-old man married to a 26-year-old woman who claimed to have been married 10 years with an 8-year-old child. Now, either they lied so the enumerator would think they were married when that baby was born, or there was some cradle-robbing going on. The bad thing is that was not the worst. There is a 50-year-old man married to a 37-year-old woman who claims to have been married 30 years. She married at age 7? Perhaps he'd been married for a total of 30 years between two marriages, but we either have a big error here or a definite case of robbing the cradle.