heridity-and-genes
heredity and genes

How does the dimensions of life and environment relate to heredity and genetics?  In this Study About Heredity we will provide information on the latest research in Genetics and other insight on the relationship between heredity and a living certain healthy lifestyle.  But, first, let’s look at the basics of heredity.

The Basics Of Heredity

Let’s start with Wikipedia’s definition of Genetics,

Genetics is the study of genes, genetic variation, and heredity in living organisms.  

For an in depth Wikipedia study on Genetics, read here.

Every cell in the body with a nucleus has the same set of complete genes.  A gene is made of DNA and is the basis of all gene instruction.  These instructions can be used for making molecules and controlling the chemical reactions of life.  Genes are the basic unit of heredity and also inheritable from parents to offspring.  Some genes are active (considered turned “on”) in some tissues organs, but not in others.  This is what determines between a liver cell and a lung cell.  Genes are switched on and off during development, and in response to influences from the environment, such as infection.

genes-and-genetics-and-heredity
Genes and Genetics and Heredity

DNA is a double-stranded molecule made up of four building blocks called nucleotide, which are different chemicals that are abbreviated as A, T, C, and G, and are arranged in a certain order throughout the genome.  DNA molecules are replicated during cell division.  When a cell divides, the two new cells contain all the same DNA that the original cell had.  The human genome has three billion pairs of bases.  The most important molecules encoded by genes are RNA and proteins.  For simplicity purposes from smallest to largest, it all starts with DNA, then DNA makes up chromosomes, which makes a cell nucleus, a nucleus is part of all cells, and cells are part of body tissue and organs.

Particulars On The Laws Of Inheritance

In the early 1800’s, Gregor Mendel, through his work on pea plants, discovered the fundamental two laws of inheritance.  He deduced that genes come in pairs and are inherited as distinct units, one from each parent.  Mendel tracked the segregation of parental genes and their appearance in the offspring as dominant or recessive traits.  He recognized the mathematical patterns of inheritance from one generation to the next.  The Law of Segregation states that each hereditary characteristic is controlled by two ‘factors’, which segregate, or separate, and pass into separate reproductive cells.  The Law of Independent Assortment states that pairs of ‘factors’ segregate independently of each other when germ cells are formed.

These laws are the foundation of genetics.  Many human traits, such as height and blood sugar, show a similar pattern, and these traits can also be inherited.  A good example, is tall parents having tall offspring.  Diseases such as heart disease, cancer, and diabetes are very complex as well.  Traits are caused by many genes and affected by the life and external factors.  Physical traits such as eye color or height are often determined by the combination of multiple genes.

mother-and-daughter-inherited-traits
Mother and Daughter Inherited Traits

The basic laws of inheritance are important because they can reveal how a genetic trait of interest or a disorder can be inherited from generation to generation.  In sexual reproduction with two parents, half of the DNA of the offspring is provided by each of the parents.  The genetic material of a child is made from 50 percent of their mother’s DNA and 50 percent their father’s DNA.  Each person has twenty-two pairs of chromosomes.  For each pair of chromosomes, one comes from the mother and one comes from the father.

There are actually two copies of each gene, one paternal in nature (father), and the other maternal (mother).  Each person also receives one sex chromosome from each parent, for a total of forty-six chromosomes.  Some species can have many more than 100 chromosomes while others can have as little as two.  Complex traits are very difficult to predict from one generation to the next.  This is because the precise combination of genes contributing to the trait can not be predicted, or perhaps, even known.

Because of the unpredictability, Geneticist look for evidence on a specific disease such as heart disease, depression, or mental illness, looking at it from the perspective of how many from the family are affected over several generations.  Recently researchers isolated a gene in over 800 families members with depression.  The study, published in the American Journal of Psychiatry, showed that at least 40 percent of depression cases can be linked to this gene, and environment and other factors make up the other 60 percent.

Gender plays a role in inheriting depressive traits, according to another American Journal of Psychiatry study which found that women had a 42 percent of heredity depression, to 29 percent for men.

inheritable-physical-traits-mother-and-daughter
Inheritable Physical Traits Mother and Daughter

Many researchers believe it’s not a single gene that causes depression but a combination of genes that lead to depression disorder.  Inheritance patterns like dominant traits show strong influence and clear patterns of inheritance, and require only one copy of a gene to express the trait. Unlike common complex traits, recessive traits require two copies of a gene to express the trait.  A carrier is one who only inherits one copy of the gene for the recessive trait.  So for a carrier, the carrier does not receive the trait.  A National Institutes of Health (NIH) Review covers different ways in which a genetic condition can be inherited.

Many health conditions are caused by the combined effects of multiple genes or by interactions between genes and the environment. The study has important medical implications for predicting the risk of a second child inheriting a disease-causing mutation from its parents.

How Stable Are Genes?

Genes can change or mutate, although this happens only rarely.  A mutation is a permanent change in DNA.  Given our trillion of cells, some mutation is occurring all the time.  While some mutations are harmful, in most cases, there is no ill effects on traits. Some mutations are beneficial.  Some are indifferent, per an NIH study.  Only mutations in sperm or egg cell can be inherited from parent to child.

One study of the Wellcome Trust Sanger Institute compared mutation rates in sperm and eggs for multi-sibling families, confirming that fathers contribute more mutations to their children than mothers.  They revealed for the first time that the rate at which mutations in sperm accumulate with age varies from father to father.  Our bodies can sometimes recognize and destroy harmful mutations, but not always.  This is how cancer cells begin.  In general, the genome is quite stable, and the genetic makeup we are born with, remains throughout life, with some exceptions:

The Gene Variables

genes-and-chromosomes
Heredity Genes ad chromosomes

Every person is born with genetic differences called variables.  Variations are why each individual is unique at the level of genes and traits.  Most variations are harmless, but some cause disease. Genetic and trait variations allows populations to adapt more readily to different environmental changes.  In fact, per this variation in population is necessary for evolution of species and natural selection, per a ScienceDaily review.   Because many traits and conditions are the results of combination of genes and environment, we see a wide range of variation for most traits in the population.

Heredity And Family History

As you learn about genetics, you will learn a comprehensive family medical history is very important because it’s, most likely, the most useful genetic test to rely on, according to the NIH. By collecting your family history over several generations, you can learn whether you may be at an increased risk for certain health problems in the future, and whether there are steps you can take to reduce your risks.  Quoting the NIH study:

Knowing one’s family medical history allows a person to take steps to reduce his or her risk.  For people at an increased risk of certain cancers, healthcare professionals may recommend more frequent screening (such as mammography or colonoscopy) starting at an earlier age.  Healthcare providers may also encourage regular checkups or testing for people with a medical condition that runs in their family.  Additionally, lifestyle changes such as adopting a healthier diet, getting regular exercise, and quitting smoking help many people lower their chances of developing heart disease and other common illnesses.

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Genetics Heredity Environment

As an example, if your family has a history of heart disease, can you reduce the risk to yourself by not smoking, getting regular exercise, and eating a healthy diet?  Yes, you can.  So, you can potentially determine certain health risk that could affect you.

Inheritance Or Environment?

Some Philosophers such as Plato and Descartes suggested that certain things are inborn, or they occur naturally, regardless of life influences.

Nativists take the position that all or most behaviors and characteristics (traits) are the results of inheritance.  Genetic traits, they believe, are handed down from parents, with individual differences which make each person unique.  Other well-known thinkers, such as John Locke, believed is what is known as “Tabula Rasa”, which suggests that the mind begins as a ‘blank slate’.  According to this theory, everything we are and all of our learned knowledge is determined by our experiences.

According to a 2009 Biotechnology and Biological Sciences Research Council study, past experience is invaluable for complex decision making.  Learning from experience actually changes the circuitry in our brains so that we can quickly categorize what we are seeing and make a decision or carry out appropriate actions.   Behaviorism is a good example of a theory rooted in Empiricism, which is the belief that most behaviors and traits are a result of learning and experiences.  Theorists such as John Watson believed that anyone could be trained to do anything or become anything, regardless of their genetic background.

Nature Versus Nurture Or Both

nature-and-nurture-and-health-and-well-being
nature and nurture and health and well being

The nature versus nurture debate is one of the oldest philosophical issues within Psychology which actually has no one school of thought.  So, what exactly is the debate about? Here are the options involved in the confusing debate:

  • Nature refers to heredity and the inheritable genes that determine who we are, from our physical appearance to our personality characteristics.
  • Nurture refers to all environmental experiences that impact who we are, including our early childhood development and experiences, our social relationships, and our surrounding culture, for the most part.
  • Nature and Nurture. Both play a role in defining personality, physicality, and intelligence.

Fairly recently, different branches of Psychology often take a one versus other approach.  Biological Psychology tends to stress the importance of genetics and biological influences. Behaviorism, on the other hand, focuses on the impact of environment has on behavior.  When a person achievers tremendous academic success, did they do so because they were genetically predisposed to be academically successful, or, is it a result of an enriched educational environment?  If a man abuses his wife and children, is it because he was born with violent tendencies, or, is it something he observed and learned by experiencing his own parents’ behavior?

It is generally accepted that certain genetic diseases, eye color, hair color, and skin color, are biologically determined characteristics.  Whereas, things like life expectancy and height, also having a strong biological influence, can also be directly influenced by environmental and other lifestyle experiences.  Height is an example of a trait that is influenced by both nature and nurture interaction.  A child might come from a family where everyone is tall, and he may have inherited the genes for height.  However, if this child grows up in a deprived environment, where he or she doesn’t receive proper nourishment, he or she might not ever attain the height because of malnutrition.

Some characteristics are attributed to the environment, influencing such things as parenting style and learned experiences.  A child might learn through observation and by reinforcement to say, for example, “please” and “thank you”.  Another child may learn to behave aggressively by observing older children engage in violent behavior.  The “Social Learning Theory” suggest that children learn to exhibit aggressive behaviors because they observe others acting aggressively and can see how these behaviors are reinforced over time, according to a Developmental-Behavior Pediatrics study (ScienceDirect).

genetics-heredity-and-family
Genetics Heredity and Family

As an example highlighting the confusion is, a perfect pitch is the ability to detect the pitch of a musical tone without any reference.  Researchers have found that without a certain inherited gene even musical training from childhood is not typically enough to possess perfect pitch, although musical training or the nurture experience of training, is also beneficial and advantageous.  In the past, debates over the relative contributions of nature versus nurture often took a very one-sided approach, one side arguing that nature played the most important role, and the other side suggesting that it was nurture that was more significant.

For example, on the nature side, a Minnesota University study of identical twins reared apart were similar to identical twins reared together, finding that genetic factors effect general intelligence and psychological differences. Another 2004 University of Minnesota study made similar claims.  A 2013 journal of Personality study found that in adult twins, genes determined their happiness, particularly, growth, self-control, purpose, and positive social interaction reinforce psychological well being.

However, today, most experts agree that both play a critical role, and interact in very important ways all throughout life.  For example on the nature and nuture side, a 2015 University of Queensland study found that a combination of complex genes at 49 percent, and environment, at 51 percent, determined ones’s health and well being.  Simply put, our bodies react to the “outside world.”  How about the outside, well, inside influence of a parent on a child?  How much influence does a parent have?  Turns out, much influence!  Parenting style can determine the intensity of a child’s behavior, just like a child’s traits influence how a parent behaves.

According to a 2011 Clinical Child and Family Psychology Review, negative parenting could exacerbate frustration, and poor self-regulation in a child, while the adverse behaviors of the child could provoke a harmful parenting style.  On the positive side, the same is true for positive traits and positive parenting styles.  A Developmental Psychology study found a similar correlation and conclusion, that a adoptive child’s antisocial traits are linked to the mental illness of biological parents, the adoptive guardian’s parenting techniques affect the adoptee’s disruptive behavior, and the other way around, as well.

genetics-environment-choices-determine-health
Genetics Environment Choices Determine Health

On the positive side, a 1962 American Psychology study found nurturing in school can cause a creative talent to bloom.  A parents decisions can determine a child’s growth and future success.  Although their genes determined their intelligence, the interaction as a parent with the child determines their progress.  Interestingly, geography, can not only influence a child’s environment, but also it’s traits.  Researchers at King’s College London’s Institute of Psychiatry concluded that a child’s risk of getting diabetes may be high because of family history, but may never contract diabetes because of the family’s custom of eating proper diet and participating in frequent family exercise.  Both positive influences through environment.

Latest research seems to backup both nature (genes) and nurture (environment) play a role in the outcome.  However, the debate still goes on.  Researchers in Psychology still often tend to emphasize one influence or the other.  Some studies explore and emphasize the nature side, and other research might conduct studies addressing how things such as peer pressure or social media, influences behavior, stressing the importance of nurture.  What researchers do know and agree on, is that the interaction between heredity and environment, is often the most important factor of all, per a Kahn Academy video (1).

According to a ResearchGate editorial “Nature, Nurture and Human Behavior; an Endless Debate”, there are simply too many “facts” on both sides of the argument which are inconsistent with an “all or none” view.  So instead of asking whether the child development is down to nature or nurture, the question has been reformulated to “How much?, considering the fact that both heredity and environment influence the person one become, which is the more important?  The study concluded:

If we are really trying to help people’s lives, it is essential to get it right.

great-health-and-well-being
great health and well being

Conclusion

Although researchers and experts still debate the degree to which biological or inheritance, and environment, influences behavior the most, few experts now take the extreme view of one, and not the other.  The reality is that there is not a simple way to disentangle the multitude of forces that exist, as this Study About Heredity has clearly illustrated.

These influences include genetic factors that interact with one another, and all of the life experiences and environment that also interact and have to be in balance, such as social experience and overall culture, as well, as how heredity and life experiences intermingle.  Modern research has moved more to investigating how genes modulate the role of life and its influence, and vise versa. What researchers do know and agree on, is that the interaction between heredity and environment, is often the most important factor of all, per a Kahn Academy video (1).

So, Where Does That Leave Us?

We now understand that both genetics and experiences and environment share a common role in developing our behavior and our character.   But, more importantly, the relationship of life and genetics interact with each other, and that interaction clearly effects overall health and well being, either in a beneficial, or harmful way.

nutrient-rich-mediterranean-diet-for-healthy-genes
Nutrient-Rich Mediterranean Diet For Healthy Genes

Finally, let’s look at some very common daily activities that we can put into practice that will go a long way in not only achieving overall happiness, health, and well being, but also maintaining it throughout our lives: