Did You Know??
The dominant allele will determine the trait that a person develops. So a combination of 1 recessive and 1 dominant allele will result in the dominant allele forming a trait. Only if a dominant allele is missing altogether, will the two recessive alleles form a trait.
There are people, so there will be traits. What are traits? Simply put, traits are certain characteristics that humans have―their behavior patterns, the ability to react to certain situations in a particular way; and more importantly―certain physical attributes. It is what makes all of us human in the true sense. Interestingly, there are certain traits that we inherit, while some others we acquire.
Acquired traits would denote that the environment we've grown in, the kind of situations we've faced, or any other such external factors have made us 'acquire' or 'take on' certain traits. Acquired traits would mainly refer to the behavior patterns.
Inherited traits in humans, on the other hand, are exactly the way they sound―we inherit them. The simplest way by which we can understand this concept is if we look at a pair of siblings. Chances are that they will look similar, have similar features, and have certain characteristic behavior patterns that they share. This is because they have inherited the traits.
There are several such inherited traits. In fact, we rarely ever stop to think about these genetic traits in humans because they have been 'wired' into us (for the lack of a better word). They are ingrained, and we therefore do not distinguish. There are inherited behavior traits in humans like anger or cooking abilities, and these are more difficult to notice. What is more easily observable are the physical inherited traits and that is what we will be dealing with today. Let us try and shed light on some of these traits through the following article. All in all, it'll make for a very interesting read and tell you a little something more about human genetics.
Physical Inherited Traits
Traits are passed from parent to child through genes and chromosomes which are made up of DNA. There are only 23 pairs of chromosomes in the human body (1 from each parent) but each of these chromosomes has several thousand genes in them. Some genes are dominant while others are recessive. The dominant genes are responsible for traits in humans, while recessive genes will only come into action if the dominant genes are missing. Thus it is these genes that will decide the inherited traits in humans. Here is a list of the commonly inherited physical traits. Use this list to see which category you fall under.
There are two kinds of earlobes. The attached earlobes and the detached earlobes. Attached earlobes are those in which the lobes are joined to the side of the head. They appear to be one complete structure. Whereas detached earlobes are those in which the lobe seems as if it is detached. They appear hanging from the ear.
Notice how some people have a straight hairline and others might have a widow's peak? Let's get to the root of that. Most genes have variations in them called alleles. These determine the way things will shape up. For example, the hairline shape has two alleles―the widow's peak or straight. The factor which determines whether a person will have a straight hairline or a widow's peak is determined by the fact whether the alleles (1 from each parent) are two identical ones or not (recessive or dominant). When a dominant and recessive allele mix, the dominant trait will be observed. Which means that if a child gets a dominant straight hairline shape from one parent and a widow's peak from the other, his hairline will be straight (since it is dominant). It is only if there are two recessive genes that come together that they will manifest to form the corresponding hairline. If not, then as a rule, the dominant allele will form the result.
Some people have straight hair while others have curly or wavy hair. It has been studied that curly hair is a dominant trait whereas straight hair comes about as a result of a recessive gene. So for all of you who have straight hair, it is because of two recessive genes that it has come about.
Try this experiment. Clasp your hands together and interlock your fingers without thinking. Now check which thumb is on top―the right or left. There is no explanation for this one, but studies have found that 55% of people place their left thumb up, while 45% place their right.
Some people's second toe (the toe after the big toe) is shorter than their big toe. While others' is longer than the big toe's length. There are theories that are formed that the latter means that the person is dominating, but that is, of course, not genetics.
Look at your thumb carefully―is it a straight thumb or a hitchhiker's thumb (one that is slightly bent backwards). A hitchhiker's thumb is rarer than a straight thumb.
Notice how some people have dimples while others don't? That's because a dimple is caused due to a dominant gene which carries the 'dimple' trait. People who do not have dimples carry a recessive gene of the 'dimple' trait.Sometimes, we also see that the parents might not have dimples and yet a child has them. This is because they are passed on from the grandparents or even great-grandparents. The dimple trait which remained a recessive gene during the parents' conception, will become a dominant gene during the grandchild's conception and therefore comes about in the form of a dimple.'
Some people are able to roll their tongue while others can't. This is due to the working of the dominant and recessive gene. Some people have the dominant gene which enables them to roll their tongue while others don't. What is interesting to note is that it is a single gene that is responsible for the presence or lack of tongue rolling. And here's something to think about―30% of all identical twins do not share the trait.
A cleft chin is rather uncommon and comes about in people as a result of a dominant gene and a recessive smooth chin gene. While in the majority of the human race, it works the other way round.
These are caused by a dominant gene and their absence denotes a recessive gene.
Here is an interesting thing to try out―spread your palm out and then try to do the Vulcan sign. Join the index and middle finger together and the fourth and the little finger together to form a 'V' sign. (Keep the thumb out of this.) Can you do it? Or is it a strain? Some people can do it easily while others just can't.
For some, the chemical Phenylthiocarbamide (PTC) tastes very bitter while for others it has no taste.
Many people inherit allergies from their parents. It is not a necessity that are always brought on due to external factors. If a parent or both parents have some form of allergies, then there is a high chance that they'll be genetically passed on to the child.
Colorblindness comes about because of a recessive allele that is present in the X chromosome. Since women have two X chromosomes, and one of these has the normal color vision allele, colorblindness in women is less likely. Whereas, since men have only one X chromosome, and they happen to inherit one which has the allele for colorblindness, it will come about as a trait. Hence men suffer from this condition more than women do.
I bet most of you had not given this a second thought, but now you will. Of course, not all inherited traits in humans serve a purpose (the ability to do the Vulcan sign or not, for example). But serve a purpose or not, these inherited traits do pass a common thread among us to evoke a general feeling of belonging and identifying with being a human.