Answer: The given statement is True.
Nuclear DNA is present in the nucleus of eukaryotic cells. When working with the DNA samples, the best source of nuclear DNA is hair root that anchors the whole shaft of hair. Hair root possesses cells that are called as keratinocytes. These cells are ideal for the extraction of nuclear DNA.
But, DNA is not always available in a hair sample as it can not be extracted from shaft of hair ( since it undergoes cornification that destroys the genetic material of the cells).
Thus, given statement is True.