John Adams and Thomas Jefferson both sported wigs early on, but based on portraits from their presidencies, they both wore powdered natural hair and eventually "naked" hair later in their careers. Powdered hair phased out around the 1800s, but shampoo as we know it was not introduced until the 1930s. So it's safe to say the 1800s were a bit...fragrant.
So, to split hairs, the founding fathers may have worn wigs early on, but the early presidents of the United States did not. And everyone basically had syphilis and lice in 17th century Europe. Suddenly "Outlander" feels a little less sexy.