The psychic is, quite literally, the new kid on the block as far a psychics go; his name is Tyler Henry, and apparently the basic cable channel E! is really pushing a TV series featuring him, Hollywood Medium With Tyler Henry. His website describes him thusly:
Mitochondrial DNA is only a small portion of the DNA in a eukaryotic cell; most of the DNA can be found in the cell nucleus and, in plants, in the chloroplast. In humans, the 16,600 base pairs of mitochondrial DNA encode for only 37 genes.
The Mitochondrion is a component of a human cell, and contains its own DNA. Mitochondrial DNA is very small, at just 16,569 base pairs (by comparison the human genome is 3.2 Billion base pairs). It is transmitted from mother to child, thus a direct maternal ancestor can be traced using mtDNA.