As humans, we inherit nuclear DNA from mom and pop. Only mama can give us her mitochondria and mitochondrial DNA.
You can thank your mama for your mitochondria. Or not. The circular DNA reminiscent of bacterial DNA resides within the matrix of each one.
What you should also know about mitochondria is that they are the agents behind The Mother's Curse.
(Cue scary music and Edward Scissorhand-Zombies.)
How can an innocent little structure, necessary to break down the delicious chocolate chip cookies from your loving mother, also give you the goose bumps when paired with a screechy organ tune?
Each mitochondrion contains its own DNA from its pre-endosymbiotic days. That DNA helps the mitochondria perform all its important cellular respiration functions by coding for proteins specific for that process. It also turns out that the mitochondrial DNA also plays a major role in male aging and fertility, with little to no consequence in females. Scientists have found that certain mitochondrial mutations are associated with a shorter life span in males or decreased ability to reproduce in flies, yet the same exact mutations in females don't have the same effects. This may explain why males have shorter lifespans than females.
That means that if the mitochondrial DNA from your mom contains "bad" mutations, they'll likely only affect you if you're male. Hence, the Mother's Curse really only applies to half of us. The male half. Aw, but don't worry guys. Mom didn't do it on purpose.
It's also likely that these little structures are therefore behind the shorter life expectancy of males. Scientists don't exactly know how, but learning more about the mitochondrial genome, and the importance of each of its genes, will help us figure all this out. It won't stop moms all over the world from passing them down to their children anymore than it would stop yours from trying to feed you Brussels sprouts when you were three, but knowledge is power and Brussels sprouts aren't really all that bad.