I don't know what research you have done alresdy but taking the information that you already have, I would suggest the following action, if you have not done so alresdy:
1. Check Jefferson Co. 1860 census for Nellie and Rhonda Igo (Igou etc.) as well as Jackson and Henry Parsons. Chances are they were still living with their parents.If parents are located in census, theeir place of birth will indicated as well as each other person in family.
2. Check 1870 Jefferson Co. census.If Nellie married in 1866, Jackson Parsons should be listed as a head of household.
3.If Nellie & Rhonda's parents are located in 1860 or 1870 census, look for them in 1880 census.In this census, the place of birth of parents of each memeber of household is indicated.
If you gain/have gained any info from the above, take it and begin to work back.I ealize this is elementary but again I don't know what research you have done already.