Here's why:
* Mitochondria: These are tiny organelles within cells that are responsible for generating energy.
* Mitochondrial DNA (mtDNA): Each mitochondrion has its own small, circular DNA molecule. This DNA is separate from the larger DNA found in the nucleus of the cell.
* Maternal Inheritance: During fertilization, the sperm contributes only its nuclear DNA to the offspring. The egg, however, provides both nuclear DNA and mitochondria.
Therefore, all offspring receive their mtDNA solely from their mother, making it a powerful tool for tracing maternal lineages and evolutionary history.