You'll have to do your own research. Examine their ages when they "left." Long after Jerrerson promised Hemings he'd free their children. The oldest two were never freed, they ran away. Madison came of age and wasn't freed, we could absolve Jefferson of letting this one slip his mind as he was in bed dying of diaharrea. Over his lifetime, Jefferson freed four slaves, at least two of whom bought their freedom. Technically, even Sally Hemings wasn't freed by Martha. You want to give them credit for things they never did.