Nuclear DNA is the genetic code that is found inside of the cell’s nucleus. Our autosomal and sex chromosomes are nuclear DNA.
When the head of the household is no longer listed, don't assume he/she is dead. It's possible that the former head of household is now living with one of the children.
Use a Correspondence Log for both regular and electronic correspondence. This includes the name and address of the person to whom you have written, what you requested, the date the request was sent, and a column for the outcome. Remembering every letter written is impossible. Follow up if you don't get an answer within a month.
[Sources & Evidence]
Public record keeping was very unorganized in previous generations.
Probate records refer to wills, inventories, letters of administration and guardianship. They are usually held at the county courthouse unless archived and they are indexed by the name of the testator.