How Do Your Genes Affect Your Baby’s Personality?

When a baby is born, the first few thoughts are about who the baby resembles more. Has s/he got his/her father’s or mother’s nose? While most parents say that newborns often resemble the father, there is no doubt that the baby resembles the mother too. The mother carried the baby for nine months and of course, the baby is always hers. But if genetics didn’t play a role, there would be no way to know certainly that the baby is indeed the fathers.

There is no research or study that claims or proves that newborns look more like their fathers. The most common and easiest way is to ask people for their opinion and this is subjective. So, how do we end up like we do and how do we act like we do?


The Act Of Genetics

Noelene Kinsley, a qualified genetic counselor practicing privately in Johannesburg says our appearance is a mere result of many genes working together. “Even a simple feature like eye color has a complex beginning and is determined by the combination of many genes and their products. But we know that the end result will be similar to someone in our family, as these genes have been passed through generations,” she says.

Genes are composed of DNA (deoxyribonucleic acid). And DNA, in turn, consists of four important chemicals, adenine (A), thymine (T), cytosine (C), and guanine (G). A DNA is made is when these four chemicals are strung together in a particular sequence to form a helical structure.


The sequence of A, T, G, and C make us appear like we do and give us the instructions to act in a certain way. Our body functions on these sequences. Enzymes digesting food, clotting factors, pigmentation are all the result of our DNA sequence. These strands of DNA carrying our genetic information, coil together to form our chromosomes.

Humans have 23 pairs of chromosomes, i.e. a total of 46 chromosomes in our body. And our reproductive eggs and sperms have 23 unpaired chromosomes each. On consummating, when a fetus is conceived, the fetus is made up of half of its mother’s genetic information (from the egg) and half of its father’s genetic information (from the sperm).


When these two genetic pieces of information combine, the characteristics of the fetus are derived such as height or eye color. While some characteristics come from a single gene, others come from a combination of genes.

Every person has about 21,000 different genes, the combinations are endless. For example, it takes a dozen gene combinations to determine the eye color of a fetus or baby. “It’s entertaining to play with the concept of trying to figure out what a baby will look like based on the parents, but the process is complex,” says Noelene.


However, your genes cannot determine if you’ll turn out to be a football player or a science whiz. Your environment, abilities, and interest play an equally important role in nurturing your personality. “Just like appearance, there are other traits that are impacted by our genetics, including behaviour and intellect,” Noelene further explains.

“The development of these characteristics isn’t simply the product of the genetic makeup but also a response to the environment. It’s a combination of genes interacting with other genes and the environment that moulds the character, and the outcome of this is obviously difficult to determine.”


Genetic Disorders

Similarly, diseases too can be caused by genetics. More than 4,000 human diseases are caused by genetic errors or mutations. However, having a genetic mutation which may lead to a condition or disease does not give a 100% certainty that you will develop that disease or condition. It takes a combination of genes along with environmental factors to develop such a disorder.

It is natural for prospective parents to rule out any possibilities or chances of genetic disorders in their baby. These genetic mutations can often be picked up screening before you become pregnant (pre-pregnancy genetic testing) or during your pregnancy (prenatal screening). But, this doesn’t mean all expecting mothers should to do this test.


“Prepregnancy screening should be considered by couples who have a personal or family history of a child born with a birth defect, intellectual delay, hearing or vision loss, chromosomal abnormality or a genetic disorder,” says Noelene.

Prenatal Tests To Rule Out Genetic Disorders

Prenatal screening involves ultrasound exams, maternal blood tests and a noninvasive prenatal test (NIPT) during your pregnancy. A noninvasive prenatal exam tests the DNA of the growing fetus to count the number of chromosomes present in the fetus.


“The blood test and NIPT are used in combination with the ultrasound to identify the chance of a chromosome abnormality, in particular, Down syndrome, Trisomy 18 and Trisomy 13. If there’s a suspected high risk for one of these chromosomal abnormalities, it would need to be confirmed with an invasive diagnostic test, such as an amniocentesis,” Noelene adds.

A NIPT can be done as early as nine weeks into your pregnancy. However, if your chances of having a baby with a genetic disorder are high, you can opt for the preimplantation genetic diagnosis (PGD) procedure. Many believe that PGD can help predetermine the child’s characteristics and change them to their suitable preferences. These babies are also called as designer babies. This type of genetic engineering can cause many problems both scientifically and ethically.

Sometimes, couples choose to conceive through in-vitro fertilization (IVF) post which the embryos are tested for any genetic disorders such as sickle cell disease, cystic fibrosis, Tay-Sachs, Down syndrome, and Huntington’s disease. After testing, the embryos free of any genetic disorders are implanted in the mother’s womb.

It is impossible for scientists to know what every gene in a human body does and how each gene interacts with the other genes. the genetic combinations are innumerable and the effects of scientifically engineering these combinations are not known yet. The long-term effects of designing genes in humans can be dangerous and problematic in various ways. It is thus best to leave it to nature to act according to its course. However, checking for any genetic disorders and taking the precautions or necessary steps is a good way of preventing a genetic disease.