Are you more genetically similar to your mother or father?

“He is the image of his father!” Or: “She is her mother’s clone – down to the nose. Clearly from their father’s side. ”When we see children growing up, we tend to look for similarities between them and their parents. So which parent contributes more genetically?

The answer depends on whether you’re asking about the total number of genes a child inherits from mom and dad, or whether the parents’ genes actually do more. But either way, scientists think the answer isn’t exactly 50/50.

For example, most people know that genes are carried on strands of DNA which are packed in an X- or Y-shape Chromosomes. These autosomes are housed in the nucleus and the DNA they contain comes from both of our parents in equal parts. But the cell actually contains another chromosome – which is hidden inside Mitochondria. The mitochondria, or the “powerhouse” of the cell, produce the energy of a cell and, according to an overview published in the magazine in 2011, play an important role in movement and aging Physiological genomes. The mitochondria also have their own set of DNA – and we only inherit it from our mother.

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“This is a clear example of how you are more like your mother than your father,” said Marika Charalambous, a geneticist at King’s College London.

Some studies suggest that our mitochondrial DNA – and therefore our mother – plays a key role in our athletic endurance. For example, Spanish and Israeli scientists studied a mitochondrial gene., This is related to the amount of oxygen cells we can use during exercise. Their study, which was published in the 2005 Journal of Applied Physiologyfound that a variant of the gene associated with lower fitness was less common in elite cyclists and runners than in the general population, a finding that was confirmed by later studies. A number of studies have highlighted the importance of mothers in the inheritance of this and other genes. They found that a mother’s ability to move alone can predict a child’s performance better than taking fathers into account.

But instead of asking which parent contributes more genes, you could ask which parent’s genes are more effective. Most of the surface-level differences we see between humans are not due to the genes themselves, but rather to a series of chemical “switches” that sit on our DNA and tell our bodies which parts to read and translate into protein and which ignore it, Charambalous told Live Science. “There are a number of genetic variations between people that don’t just affect the sequence of genes,” said Charambalous.

In a phenomenon known as imprinting, these switches turn off certain genes completely – but only if they came from a particular parent. These patterns persist for generations. For example, if the ‘A’ gene is paternal, it will always work if it came from your mother, but never if it came from your father. Most studies suggest that there are between 100 and 200 imprinted genes in the body. However, some research suggests that there could be more, according to an article published in the journal in 2012 PLOS Genetics. These genes are particularly important in the brain and in the placenta.

There is some disagreement about whether imprinting affects gene expression towards one parent or the other. There is evidence that there are similar numbers of maternal and paternal imprinted genes, said Andrew Ward, a geneticist at the University of Bath in England. “In the traits that gene imprinting is responsible for, you are in some ways more like one parent than another,” Ward told Live Science. In other words, imprinting can affect certain traits – from our height to sleep and memory. But because imprinting occurs on relatively few genes, and those genes are likely balanced between parents, imprinting won’t determine whether you have any remarkable resemblance to mom and dad, Ward said.

However, studies in mice suggest that there may be an imbalance in this regard that favors fathers. A study published in the journal in 2015 Natural genetics found that imprinted genes are 1.5 times more likely to be silent on the mother’s side and active on the father’s side. An earlier study published in the journal in 2008 PLUS ONE found a similar result. Most of the imprinted genes were active in the brain if they came from the father. The opposite was the case in the placenta. However, there is at least no evidence yet that such an imbalance occurs in humans.

But even if imprinted genes affect gene expression from one parent over the other, it wouldn’t necessarily make you more like that parent. After all, the gene that is active in you might be silent in you, said Edward Chuong, a genome biologist at the University of Colorado Boulder.

“You can say it [your gene expression] Thanks to your parents, “Chuong told Live Science.” But it’s complicated to say that it is similar to your parents. ”

Originally published on Live Science.