Science Solitaire

[Science Solitaire] Why each of us got more from Mom than we did from Dad

Maria Isabel Garcia
[Science Solitaire] Why each of us got more from Mom than we did from Dad

Illustration by DR Castuciano

'[I]n terms of DNA, you have to know that you got more DNA from your mother than from your father – all of us did'

Each of us is a mix of what our parents gave us. That applies to how they raised us and the initial genetic pack they passed on to us – our DNA. But in terms of DNA, you have to know that you got more DNA from your mother than from your father – all of us did. 

At the center of each of your trillions of cells are intertwined fibers called DNA. One strand comes from Mom and the other, from Dad. But outside the center of a cell are other cellular parts. One of them is the mitochondrion, which serves as the “power plant” of your cell. We have many mitochondria in each of our cells. Each mitochondrion also houses DNA, albeit much smaller and containing fewer genes than nuclear DNA. That DNA is called mDNA, which, as you would expect, scientists named as such to stand for “mitochondrial DNA,” but which might as well also mean “mom DNA,” because ONLY mothers can pass it on to their children. 

Whether you are a son or a daughter, your mom passes on her mDNA to you. So men also have their mDNA, but somehow it “decays” in their possession, and so they never get to pass it on. Only women are able to “preserve” mDNA to be passed on. 

This is one of the fundamental ways family tree services can put your family line together when you give them your DNA sample. They get your mDNA, which gives direct evidence of the chain of life traced through your mother’s line.

This is also how scientists were able to trace the entire history of modern humans – all of us living now – back to one common maternal genetic ancestor. They tagged this ancestor “Mitochondrial Eve,” and while the term loads it up with religious meaning, it has to be clarified that it did not mean that there was one individual female who gave birth to thousands and so on and so forth. But yes, it grounds our sense of humanity – that we are ALL connected in a very fundamental way in nature – across time, across distances, across political, religious, and social boundaries.

Just like the more popularly known DNA, mDNA also has genes, but a lot fewer. DNA has about 25,000 genes while mDNA has about 37. These 37 genes code for functions that have to do with powering your cells, which is how we are able to function. But like the better known DNA, it mutates as it is passed on. Mutations are small changes that happen as they are passed on. These changes, even if they are small, may sometimes spell maladies that affect your health. 

So that is why your mother gets an additional shoutout if you were to give thanks to her genetic gift pack. But you must know that mDNA is passed on NOT ONLY by human mothers but also by “mothers” in animals, plants, and fungi, which are comprised of many cells like us humans. In fact, mDNA was first found in 1963 in chicks, by a married couple who were both scientists, Margit and Sylvan Nass.  

This makes mDNA one of nature’s ancient keys to continuity – like if you had a quilt that is passed on from one generation to another through the maternal line, with each generation doing their own quilted contributions on the basic quilt.

My mother’s face, her powerhouse of inner energy, among many other things, are undoubtedly imprinted in me. She cares very little about the science of anything, but gave birth to someone like me who is passionate about it more than any other thing she wishes I were interested in. So Mom, thank you for the extra gene pack, but much more, thank you for giving me life to ponder the mystery. – Rappler.com