Who has the final say on whether one's physique is good or bad? Is it determined by nature or nurture?

Winter is the season that tests people's physical fitness the most, especially children. Their physical fitness is both their own "armor" and their parents' "weakness". After all, constant colds and fevers make parents and children collapse. Therefore, the topic of physical fitness has always been a hot topic among people. Some people believe that physical fitness is innate, coming from the inheritance and genes of parents; others believe that physical fitness can be built after birth, and that the baby's physical fitness can be improved through exercise, enhanced nutrition, etc. So what determines the quality of physical fitness? Let's talk about it today.

01. What factors influence physical constitution?

Absolute content is of course unscientific. The baby's physique is definitely the result of the combined effects of nature and nurture. But if we must rank them, the influence of nature may be greater.

There are two main factors that play a role in a baby's physique, namely genes (heredity) and environment, and both of these aspects are greatly influenced by congenital factors.

02. Genes are the main cause of traits

Genes determine traits, this is a sentence that many people are familiar with, and it is in line with the basic principles of biology. Any structure of our body is essentially inseparable from genes, whether it is appearance, height, weight, or even our response to the outside world, which is essentially determined by genes.

Genes are transcribed into RNA and then translated into proteins to regulate various conditions of the body. Because of this, the influence of genes on individual qualities is crucial. Take height, which is familiar to everyone, as an example. Height is a quantitative trait. Although we still have not fully understood which specific genes control height, from a genetic perspective, it is found that height is greatly affected by genetic factors.

Experiments on identical twins show that even if different twins experience different postnatal environments, dietary changes, and living habits, their heights are highly correlated. Further calculations show that the heritability of their height is around 70%[1]. In other words, 70% of a person's height is determined by genetics. Other traits are basically similar, after all, genes determine traits. This is also one of the roots of the saying "Dragons give birth to dragons, phoenixes give birth to phoenixes."

03. Development is also an important factor in traits

Genes are a key factor in determining traits, but they are not the only factor. In fact, another important factor that affects traits is development. The development of a baby starts from scratch. For example, the germ layers begin to differentiate from each other in the blastocyst stage, and different organs develop further. For example, the heart begins to develop around the sixth week, while the ears develop around the ninth week.

This series of developmental processes is very easy to be affected. After all, genes work together with the environment and will also respond to external stimuli. A typical example is the influence of various drugs. If the mother takes drugs that may interfere with development during pregnancy, it will affect the baby's development. In severe cases, it may even cause the baby to have developmental disorders or deformities. Because of this, many drugs will clearly indicate "not for use by pregnant women". This is the reason.

It can be said that it is not easy to give birth to a healthy baby. He is affected by the genetic genes of his parents and the mother's own condition during pregnancy. These factors can be considered congenital, which is why I think the influence of congenital factors is more important.

Of course, not only that, even after the baby is born, the influence from the innate environment continues, a typical example is: breast milk. Breast milk mainly brings three benefits.

04. Benefits of Breast Milk

So what are the benefits of breast milk?

First, energy and nutrition. As the most basic need of life, obtaining energy is an instinct and the most basic condition for maintaining life. Breast milk is the natural food source for babies and is naturally the first need of babies. As a mammal, newborn babies cannot rely on other food sources, and breast milk provides the best nutrition for babies, ensuring the energy and nutritional needs of babies. It can be said to be the best natural source [2].

Second: the ability to cope with the risks of this world, that is, immunity. One thing that many people are not familiar with is that breast milk is not just milk, it also contains immune proteins.

The human immune system is divided into the innate immune system and the acquired immune system. The former is like our skin barrier, but the antibodies that everyone is familiar with to resist diseases belong to the acquired immune system. Since it is the acquired immune system, as the name suggests, it is acquired only after birth, that is, it only starts to exist after birth, so the acquired immune system is a process of continuous establishment, and this process will last for many years. For newborn infants, its specific immunity is basically 0. Facing a world that is completely different from the amniotic fluid, it is extremely fragile. Microorganisms in the air, microorganisms on clothes, and other ubiquitous microorganisms are threatening the baby's health at all times.

Fortunately, breast milk contains a considerable amount of immune substances, such as antibodies and cytokines [3]. These antibodies can reach the baby’s body through milk fat globules and exosomes, helping the fragile baby to resist the invasion of harmful microorganisms from the outside world, thus ensuring the baby’s healthy growth.

Third: Establish intestinal flora. Intestinal microorganisms are a huge part of the human body. The total number of intestinal microorganisms can reach trillions, which is many times the total number of human cells, and their species also reach thousands, which is several times the number of human cells. Such a large number of intestinal microorganisms play a very important role in the human body.

Our digestion mainly takes place in the intestines, and in this process, intestinal microorganisms play a huge role. They not only promote our digestion and absorption, but also help us deal with nutrients that we cannot digest.

In addition, we ingest many microorganisms during our diet. These microorganisms do not interfere with the normal functioning of the intestines. Intestinal microorganisms play a huge balancing role. They secrete corresponding immune substances to kill harmful bacteria, thus achieving immune balance [4].

05. How do microorganisms colonize the intestine?

Intestinal microbes are not innate, they are also established after birth. Therefore, this raises a serious question: how do microbes survive and colonize in an empty intestine? How do they avoid being killed by the immune system in breast milk?

The answer lies in the presence of another substance in breast milk, human milk oligosaccharides (HMO), which plays an important role in the colonization of intestinal microorganisms[5].

First of all, HMO is a nutrient for intestinal microorganisms and a common nutrient in intestinal flora. For example, the familiar beneficial bacteria Bifidobacterium uses HMO as one of its food nutrition sources. Because of this, intestinal microorganisms can gradually grow and develop when the baby only consumes breast milk.

Secondly, HMOs have immune effects. They can form a natural defense barrier in the intestines, preventing common pathogens such as Escherichia coli, Salmonella, and Helicobacter pylori from adhering to the surface of intestinal cells, thereby preventing these pathogens from invading the human body[6].

It can be said that HMO is both nutritious and immune. This is the huge role of HMO in caring for intestinal microorganisms, and it is also a natural gift from breast milk.

This is why the World Health Organization officially recommends breastfeeding. In fact, the principle of human beings is basically applicable to all mammals. All creatures that need to breastfeed basically have basic nutrients, antibodies and human milk oligosaccharides in their breast milk.

However, there are still differences between species. Natural breast milk nutrition can provide more comprehensive care for the baby's health. This is why we choose to add human breast milk oligosaccharides to baby formula.

In short, the baby's physique is more affected by congenital factors. Marriage examinations and pregnancy examinations are necessary and important measures. This is also a reflection of the parents' responsibility for the new life, so that the baby can have a good physique when it is conceived.

1. Li, Miao-Xin, et al. "A major gene model of adult height is suggested in Chinese." Journal of human genetics 49.3 (2004): 148-1

2. Ballard, Olivia, and Ardythe L. Morrow. "Human milk composition: nutrients and bioactive factors." Pediatric Clinics 60.1 (2013): 49-74.

3. Parigi, Sara M., et al. "Breast milk and solid food shaping intestinal immunity." Frontiers in immunology 6 (2015): 415.

4. Arumugam, Manimozhiyan, et al. "Enterotypes of the human gut microbiome." nature 473.7346 (2011): 174-180.

5. Bode, Lars. "Recent advances on structure, metabolism, and function of human milk oligosaccharides." The Journal of Nutrition 136.8 (2006): 2127-2130.

6. Lin, Ann E., et al. "Human milk oligosaccharides protect bladder epithelial cells against uropathogenic Escherichia coli invasion and cytotoxicity." The Journal of infectious diseases 209.3 (2014): 389-398.