Mitochondria – The inheritance we forgot to see

Picture Credit: Lakshmi Ambady

“DNA neither cares nor knows. DNA just is and we dance to its music”-Richard Dawkins, British biologist.

In many families, a son is often viewed as the carrier of the family line. The family name passes through him. Property may pass through him. Ritual responsibilities may pass through him. In many traditions, great importance is placed on the birth of a male child because he is seen as the one who continues the lineage. Yet biology tells a more complicated story. There is a quiet inheritance that moves through human history without surnames, without legal documents, and without public recognition. It passes through mothers.

Every person alive today carries mitochondrial DNA inherited almost entirely from their mother. Your mother’s mitochondrial DNA came from her mother. Her mothers came from her mother. And so on, through an unbroken chain of women stretching back thousands of generations. This lineage has never been interrupted. The remarkable thing is that your father also carries his mother’s mitochondrial DNA. But he cannot pass it to his children. The chain continues only through daughters. In a purely biological sense, every living human is connected to an ancient line of mothers.

For centuries, many societies have focused their attention on paternal inheritance. Family trees often follow fathers and sons. Surnames follow fathers and sons. Historical records frequently follow fathers and sons. But there is another family tree hidden inside every cell of the body. It follows mothers and daughters. One lineage is visible. The other is invisible. One is recorded in documents. The other is recorded in biology. Neither is more important than the other. Human beings inherit nuclear DNA from both parents. We are products of mothers and fathers alike. Yet it is interesting to notice how cultural attention and biological attention do not always point in the same direction.

In many parts of India, the desire for sons is historically strong. Sons are often viewed as the continuation of the family. Daughters are seen as belonging to another household after marriage. The cultural story says - “The son carries the lineage.”

The biological story quietly replies- “The mother carries something that has been passing uninterrupted through generations.”

This is not an argument against sons. Nor is it an argument in favour of daughters. It is simply an invitation to see the whole picture. Human life exists because of both. A father contributes half of the child’s nuclear DNA. Without fathers, there are no children. But the energy-producing mitochondria comes only from the mother. The body itself carries a record of this maternal inheritance. Perhaps what is most fascinating is how easily we overlook things that are quiet. A surname can be seen. Mitochondrial DNA cannot. A family tree can be drawn on paper. A cellular lineage cannot. The visible often receives attention while the invisible remains unnoticed. This pattern appears not only in genetics but throughout human life. We tend to celebrate what can be counted. We overlook what quietly sustains us.

A mother’s labour often goes unseen.

A mother’s emotional presence often goes unseen.

A mother’s sacrifices often go unseen.

And in a strange way, the biology of inheritance mirrors this reality.

The maternal line is literally present inside every cell, yet most people never think about it. For generations, many women were told they were not carrying the family forward. Yet within them existed one of the oldest and most continuous inheritances on Earth. An inheritance older than kingdoms. Older than religions. Older than nations. A lineage that has travelled through countless mothers, surviving famine, migration, war, disease, and the rise and fall of civilizations. Every one of us is alive because that chain was never broken. At some point, a mother carried a daughter. That daughter became a mother. Who carried another daughter who became another mother. Again, and again. For thousands of generations. Until eventually, the chain arrived here. Inside you.

The lesson is not that mothers matter more than fathers. The lesson is that reality is often larger than our cultural stories. When we look carefully, we discover that life has always been carried by both masculine and feminine forces, both fathers and mothers, both visible and invisible inheritances. And sometimes what appears to be the quieter contribution turns out to have been present all along, hidden in every cell of the body, waiting for us to notice it.

And now the real question- what is mitochondria?

Every cell in your body contains tiny structures called mitochondria. They are often described as the cell’s “power plants” because they help produce the energy that keeps cells alive and functioning. What makes mitochondria unique is that they contain their own small amount of DNA, called mitochondrial DNA (mtDNA), which is separate from the DNA stored in the cell nucleus.

When a baby is conceived, the egg and sperm contribute genetic material in different ways. The egg is a very large cell and contains thousands of mitochondria whereas the sperm is a very small cell whose main job is to deliver nuclear DNA. It contains very few mitochondria, located in its tail. At the time of fertilization, the mother’s egg contributes virtually all the mitochondria to the embryo because the sperm’s mitochondria usually do not enter the egg as the tail is actively destroyed shortly afterward. As a result, almost all of a person’s mitochondrial DNA comes from their mother.

This creates an unbroken maternal chain:

Mother → Child → Grandchild (through daughters) → Great-grandchild

A mother passes her mitochondrial DNA to both sons and daughters, but only daughters typically pass it on to the next generation.

For example- A woman has two children: a son and a daughter. Both children inherit her mitochondrial DNA. The son carries it throughout his life but usually does not pass it to his children. The daughter passes that same mitochondrial DNA to her own children. This means that your mitochondrial DNA is essentially the same genetic lineage as your mother’s, your maternal grandmother’s, your maternal great-grandmothers, and so on, stretching back through thousands of generations.

From an evolutionary perspective, scientists use mitochondrial DNA to trace maternal ancestry because it changes relatively extremely slowly over time. By comparing mitochondrial DNA from people around the world, researchers concluded that all living humans share a common maternal ancestor who lived roughly 150,000–200,000 years ago in Africa. This woman is often called Mitochondrial Eve. She was not the first woman, nor the only woman alive at that time but she is simply the woman whose maternal line survived uninterrupted to all humans living today.

Human inheritance is multidimensional. The scientific lesson is not that one parent matters more than the other. It is that inheritance is far more complex than the cultural idea of a single-family line. Biology, therefore, does not tell a story of one lineage. It tells a story of many lineages intersecting in a single human being. It tells the story of YOU.

“Beauty queen since seventeen, at least to me

I was born with it

Maybelline is good to me, but I believe

I was born with it

I'm workin', workin, workin', I've been working on myself

But I can't take cred 'cause it's from somebody else

Watch me work it, work it, work it, I've been sweating on myself

All them boys, all them girls, make them stop

How you get that bod?

Is it from God?

Did you work real hard?

G-E-N-E-T-I-C-S

How you get that bass?

Is it all fake?

Made in LA

G-E-N-E-T-I-C-S

G-E-N-E-T-I-C-S

My DNA is graded A

You see this face, I was born with it

I ain't ashamed to say one day I might upgrade

I could fuss with it

I'm workin', workin, workin', I've been working on myself

But I can't take cred 'cause it's from somebody else

Watch me work it, work it, work it, I've been sweating on myself

All them boys, all them girls, make them stop

How you get that bod?

Is it from God?

Did you work real hard? (Oh)

G-E-N-E-T-I-C-S

My genetics.”

G-E-N-E-T-I-C-S- by Meghan Trainor released in 2020.