What is genetics?
Genetics is a field in Biology that studies how genes that determine particular traits are passed down from parents to offspring. Genes encode information about your traits such as eye color, hair color, height, and other characteristics. On the other hand, genes passed can also be increased risk factors for certain diseases such as cancer. Therefore, the field of genetics has been and continues to be an active area of research to understand the inheritance of specific genes.
What is a gene?
Genes are made of DNA, which carries genetic information and belongs to a larger structure called the chromosome. Humans have 23 pairs of chromosomes, so a total of 46 chromosomes, where 22 pairs are autosomal, and one pair is sex chromosomes. There are an estimated 20,000 genes in the chromosomes, which are referred to as our human genome.
How do genes work?
Genes are the blueprint of the human body that makes proteins that have various vital functions that include the storage of information, digestion, and transport of nutrients. It is estimated that one gene can produce up to 10 different proteins in the body! Every individual has a specific set of genes that are unique to them. Moreover, even family members have a slightly different mix of genes. It has been demonstrated that two humans share up to 99.9% of the same genetical material! We are all more similar than we think, but it is that 0.01% that makes us unique.
How are traits passed from parent to offspring?
Genes are the basic hereditary unit in living organisms, which contain instructions on certain functions such as the passing of genes to offspring. Parents are able to pass characteristics such as eye color, blood type, hair color, and other features to their offspring. They are also able to pass certain diseases such as cancer. Alleles are variations of a gene that are found in one copy in mom and one copy in dad. The two alleles are shuffled and passed down to the offspring. This inheritance differs depending on the interaction between the alleles.
Possible inheritance patterns include:
1. Autosomal: A gene is located on an autosome (non-sex chromosome) with both sexes being equally affected.
a. Recessive: Two copies of the allele are needed to express the trait. Examples of these include cystic fibrosis and sickle cell anemia.
b. Dominant: Only one copy of the allele is needed to express the trait. Examples of these include Huntington’s disease and muscular dystrophy.
2. X-linked: A gene is located on an X-chromosome with both sexes being unequally affected.
a. Recessive: Two copies of the allele on the X-chromosome are needed to express the trait. Examples include red-green color blindness and hemophilia A.
b. Dominant: Only one copy of the allele on the X-chromosome is needed to express the trait. Examples of these include Goltz syndrome and fragile X syndrome.
3. Y-linked: A gene is located on a Y-chromosome. For example, the sex-determining region (SRY) is a known Y-linked gene.
4. Mitochondrial: A gene is located in your mitochondrial DNA.
The debate of nature vs. nurture
Over the past decade, there has been an ongoing debate about whether genes (nature) or the environment (nurture) affect the perception of attractiveness. Many twin studies have demonstrated that the individual’s unique environment is a significant contributor to how others rate their attractiveness. Therefore, the environment is a much more critical determiner of the perception of physical attractiveness compared to genetics. However, researchers are starting to realize that this is no longer a one-sided debate, but rather both processes are very much intertwined and interconnected.
Why are some people more attractive than others?
According to Charles Darwin’s theory of natural selection, changes occur over time to confer an advantage to an individual’s fitness and survival. Therefore, if individuals with good genes are selecting attractive partners and passing their good genes along, then why are some people still more attractive than others? By Darwin’s theory of evolution, attractiveness should have become a trait possessed by all due to the evolutionary advantage it provides for procreation, however, this is not the case in the real world. This paradox has become the epitome of evolutionary biologists.
The “lek-paradox” has been criticized by scientists since it suggested that genetic variation is maintained even with the constant selection from females of males with good genes. Researchers have attempted to answer why we still find great genetic diversity, even with sexual selection. A study by Petrie and colleagues revealed that the genetic diversity observed was associated with DNA repair kits in the body. DNA repair kits are a pathway that aims to repair the damage done to the cell’s DNA due to the accumulation of mutations. As such, some individuals might have less effective repair kits than others resulting in more considerable genetic variation in their DNA as the damage does not get repaired. This study was able to underline that the reduction in genetic diversity from the sexual selection is counterbalanced by the mutations in the DNA causing an increase in diversity.
Genes linked with attractiveness
To date, researchers lack an understanding of the role of genes in the physical attractiveness of individuals. Previous studies have demonstrated that there is no master gene that controls attractiveness but rather a combination of various genes that affect attractiveness. Moreover, results illustrated that role of genes was sex-specific. Genes in females that were considered attractive were linked to body mass and lipids, while genes in males that were considered attractive were associated with cholesterol levels (Genes: CERS2, ANXA9, Trait: FC-MS).
A study evaluated 13,000 British couples’ gene composition to investigate how physical traits are chosen by individuals. The study displayed that individuals are more attracted to partners that resemble themselves. For example, height was an important factor showing the similarity in height between partners was driven by the physical appearance of the partner. Other studies have revealed that there exist multiple genes that are associated with facial symmetry and facial masculinity, which contribute to increased physical attractiveness.
Genes alone are not the sole determinants of an individual’s attractiveness there are other factors such as an individual’s environment that can play a role in influencing physical attractiveness. For example, a study by researchers exhibited that two copies of the MCR1 gene are associated with youthfulness. Though, it is not fair to say that having one copy of the MCR1 gene is to blame for looking old. Researchers argued that these genes, combined with other risk factors such as smoking, can truly affect an individual’s appearance. Nevertheless, there is a genetic basis for attractiveness, and it is essential to identify genes that are associated with physical traits.
In conclusion, genetics is an important branch that focuses on how genes are inherited from our parents. Researchers have yet to understand the underpinnings of genes and physical attractiveness. Nevertheless, recent advances have suggested that multiple genes contribute to an individual’s physical attractiveness. Future studies should aim to identify these genes in hopes of potentially understanding why certain individuals are more attractive than others.