This gene was named Igf2. It is responsible for the production of the hormone insulin-like growth factor produced in the cells of the placenta. It increases the pregnant woman’s insulin resistance, which causes more glucose to reach the fetus. In a series of experiments on mice, Cambridge scientists showed that when the placental cells did not have an active copy of the Igf2 gene, fewer nutrients reached the fetuses. The mice did not develop properly, were smaller than average at birth, and their offspring showed symptoms of diabetes and became obese relatively early.
Not all researchers are convinced of this, but those at the University of North Carolina School of Medicine have shown that it is the father’s genes, not the mother’s, that determine our individuality.
A certain regularity has already been discovered in humans: genes received from the father tend to support the growth of the fetus, while those from the mother limit it. Two other genes that influence the development of the child in the womb are also fighting a similar battle.
Scientists at the University of Bath have shown in mice that the Grb10 gene inherited from the mother controls the supply of nutrients that pass through the placenta. This limits the development of the child and promotes a thinner body, while the Dlk1 gene inherited from the father has the opposite effect – it promotes fat storage and the children are born larger.
From my father – intelligence and obesity
There are thousands of genes whose activity depends on whether we get them from our mother or father. Dr. Catherine Dulac and Dr. Christopher Gregg of Harvard University have shown that up to 1,300 genes are constantly fighting over which ones will influence the developing brain. In studies on mice, they found that during fetal life, the mother’s genes have the decisive influence, but later DNA fragments inherited from the father begin to dominate. What’s more, the influence of paternal genes can persist even into adulthood.
They are particularly active in the cerebral cortex, which is responsible for thinking, reasoning, creating and speaking. This could therefore mean that brain function and intelligence depend on the father. However, not everything good comes from the father. Scientists from the University of Southern Denmark argue in “Nature Communications” that we inherit our tendency to obesity from the father. The variant of the H19 gene from the father promotes the development of white adipose tissue, which accumulates in the abdomen, thighs and buttocks, and can cause, among other things: obesity, diabetes, cardiovascular diseases and metabolic disorders. In turn, the amount of brown fat we have will depend on the fragment of DNA inherited from our mother, believe the Danish scientists. Brown fat is sometimes called good fat because it increases metabolism and helps maintain a healthy weight.
A different gene from the father can influence a woman’s fertility, scientists at the Gulbenkian Institute of Science in Portugal have shown. The evidence was provided by research on centrioles, or organelles in the egg responsible for cell division. Centrioles usually have a covering that protects them, but over time this breaks down and causes the centrioles to be eliminated. If they are not eliminated, women are infertile.
Scientists who conducted a series of experiments described in “Science” showed that centrioles are eliminated gradually and first lose their coating and only then disappear on their own. – When we artificially preserved the mother’s centrioles, the resulting embryo had too many of them, which resulted in abnormal divisions and developmental arrest. This shows that the elimination of centrioles is crucial for sexual reproduction, explains Mónica Bettencourt-Dias, leader of the team. The scientist assures that although the study was carried out on fruit flies, its results can be applied to humans. The mechanism by which centrioles disappear in the egg occurs in all animals that reproduce sexually.
From my mother – ADHD and baldness
Genes inherited from our mother, just like those from our father, can be good or bad. And yes, we can have difficulty concentrating and mood disorders after our mother. A study published in JAMA Psychiatry shows that if a woman has low levels of serotonin, a brain chemical associated with mood, her children are more likely to develop attention deficit hyperactivity disorder.
Daughters can inherit a tendency toward depression from their mothers. Many animal studies have shown that female offspring are more susceptible to maternal prenatal stress than male offspring. Scientists came to this conclusion after observing changes in a region of the brain called the corticolimbic system, which regulates and processes emotions and plays a role in mood disorders. A similar relationship has been demonstrated by scientists at the University of California, San Francisco, in humans. They proved that disorders in the functioning of the corticolimbic system are more often passed on from mothers to daughters than from mothers to sons or from fathers to sons of either sex. “This does not mean that mothers are responsible for their daughters’ depression, but it suggests that genes inherited from the mother may be one of many factors that play a role in the development of this disease,” says Dr. Fumiko Hoeft, lead author of the study.
Men can inherit a tendency to lose hair from their mothers, scientists from the universities of Bonn and Düsseldorf have shown, and published the results of the study in “PLoS Genetics”. They analyzed more than 55,000 men, some of whom suffered from baldness before the age of forty, and some who had luscious locks after the age of 60. Scientists found almost 300 genes associated with male pattern hair loss. They found 40 of them, including the androgen receptor gene, only on the X chromosome, meaning they were inherited from the mother. The remaining genes were spread across DNA inherited from both the mother and the father. Interestingly, some of the genes responsible for hair loss also appear to be associated with an increased risk of heart disease in men.
Parental stigma
When we observe children growing up, we often look for similarities with their parents. For years, it was believed that there was complete equality in this regard. Sometimes the mother’s gene is activated and other times it is from the father. This suggests that we are similar to each other to the same extent and inherit our character traits, temperament and propensity to disease in the same measure.
A few years ago, scientists at the University of North Carolina School of Medicine showed that genetically we have more in common with our father than with our mother, because his genes, not those of our mother, have a greater impact on us and mainly determine our individuality. For reasons that are unclear, we most often use fragments of DNA inherited from our father. The scientists did not study humans, but mice. By crossing them in different ways, they checked when the genes from the father and when those from the mother were active. They found that the fragments of paternal DNA were much more likely to be included.
The mechanism that determines which DNA fragments the body will use is called parental imprinting. It involves activating or blocking certain genes in the egg and sperm before fertilization. The child therefore receives two copies of the gene – one from the father and one from the mother, but only one is active. When there is an error in this imprinting, diseases arise.
However, not all researchers are convinced that our father’s genes have a greater influence on us. Genes that come equally from both parents are located in the cell nucleus, but the fertilized cell contains another set of DNA that is hidden in the mitochondria. We only inherit this from our mother. This suggests that we have more in common with our mother than with our father.
And our tendency to high blood pressure may be written into our mitochondrial DNA, scientists from Cincinnati Children’s Hospital Medical Center and the Medical University of Vienna have shown. They studied a large family from northern China. 15 of its 27 members, descendants of the same ancestor, had blood pressure above 140/90 mmHg (normal 120/80 mmHg) even after treatment. Scientists have shown that this disease is the result of a mutation in a gene located in the mitochondrial genome, which we inherit only from our mother.
Mitochondrial DNA also influences our physical endurance, say scientists in the Journal of Applied Physiology. Depending on the variant of the gene related to the number of oxygen cells used during physical activity that we receive from our mother, we can become a professional cyclist or runner, or we may not even count on an athletic career.
Because we receive more genes from our mother, we can also inherit more diseases. Mutations occur in both the DNA of the nucleus and the mitochondria. Mitochondrial diseases, of which more than a dozen have been described, mainly disrupt the functioning of the nervous system and skeletal muscles. Children of both sexes can suffer from them because each child inherits mitochondrial DNA from its mother.
The situation is different with sex-linked genetic diseases caused by genes located on the X or Y sex chromosomes. As we know, the sex of the child depends on whether the sperm contains an X or a Y chromosome. When the mother’s X chromosome combines with the mother’s chromosome, it produces a girl (XX), and when the Y chromosome combines with the mother’s chromosome, it develops into a boy (XY). So if a man has a mutation on the only X chromosome that causes a disease, for example, color blindness, he will have color vision disorders. A woman usually sees colors correctly because the correct version of the gene present on the second X chromosome protects her against color blindness. However, she will still be a carrier of the disease. Hemophilia is inherited in the same way.
