DNA and ancestry: Who are we? (Part 1)

Did you know that your DNA can answer questions about your past, present as well as future? Your DNA is the genetic material that gives you your naturally inherited characteristics. DNA will tell you about your ancestry because it tracks all the characteristics that you inherit from your past several generations. It also contains the genes that define your present characteristics. In addition, even your traits can be predicted effectively using your genes. Your physical traits like eye color or simple genetic diseases can be predicted as well as altered using existing technologies such as CRISPR – based genome editing. New research also shows that your psychological traits like intelligence can also, possibly, be predicted and altered.

The subject of DNA and its life-changing capabilities may not be immediately interesting to you, but to those who understand the importance of genetics and ancestry, it is of huge significance. In this two part series, we explore what past our DNA and ancestry holds for us, and what it can do for our future.

Why must everyone know about DNA and genetics?

To put it in simple words, DNA contains genes, genes make proteins, proteins make cells and cells make you! You are the successful final product of all the hard work of your genes. And we must identify and learn about our genetics first if we have to identify ourselves. There are many different methods that you can follow to study yourself. But before we come to that, did you know that your entire genomic sequence is close to 12.8 GB and can be stored on a DVD?

Your gene is basically your body’s instruction manual. It is a small section of your DNA. Your DNA, including genes, is made up of chemical bases, and the entire sequence of bases forming your genes is called your genomic sequence. This is the section that forms you and comes in handy in DNA and ancestry studies. You inherit half of your mother’s genes and half of your father’s genes, and a combination of those will give you your properties based on which gene is dominant. And the selection of the genes is random, which is the reason why you are different from your siblings. You both inherit the same set of genes from both parents, but the selection of which genes are finally used is completely random and different in you and your sibling. Sometimes, these genes can be inherited in you in the form of a variant, which is a slightly different form of the same gene. Variants may or may not pose a problem. In some cases, they do, which causes the so-called ‘genetic diseases’. This is because your genes are your body’s instruction manual, and a slight change in instructions has the capacity to induce substantial changes to the proteins in your body.

Now that we are clear on how genes work, we must realize that scientists study genetics so that our family relationships and ancestry can be studied. Most importantly, any illnesses due to defects in your genomic sequence can be detected early and rectified if possible. Coming to the interesting part now, it is common knowledge that we have services that find out your family genealogy for you using just your saliva sample. What happens behind the scenes? Let’s take a look.

Ancestry tests

Your genes are your blueprint. We have already established that you get half your genes from your father and the other half from your mother. Your DNA is contained in chromosomes, which are contained in the nucleus of every cell in your body. Every cell has 23 pairs of chromosomes, which makes 46 chromosomes in all. But why am I telling you all this? This was necessary to establish the fact that you are receiving one set of chromosomes from your father and one set from your mother, making 22 pairs. And there is one pair that determines your sex. This is the normal scenario for that one pair shown below:

As you can see, the mother gives two X-type chromosomes and the father gives one X and one Y-type chromosome. XX forms a girl and XY or YX forms a boy. There are variations to this scenario that can make different variations in sexes. Not all XXs are girls and not all XY or YXs are boys. A combination of XXY or YXY can also be produced among others, which can form several types of genetic conditions other than boy or girl. For example, a person having an XYY chromosome type will be a boy having an extra Y chromosome, which can have some minor effects like having more than average height, increased acne, increased risk for disabilities, etc. In another scenario, XXY chromosomes will mean a boy having an extra X chromosome (Klinefelter Syndrome), which can have effects like more than average height, weaker muscles, risk of language or reading impairment, etc. Likewise, there can be numerous combinations of chromosomes that determine the physical and mental properties of a person in different blends.

The purpose of this explanation was to explain that these X and Y chromosomes are used by ancestry tests. There are three main types of these tests as I show here:

• Y chromosome testing: Y chromosome is tested to determine the male line ancestry. Since females do not inherit the Y type chromosome, this test can be taken by males. Typically, if a woman wants to get these tests done, they would usually get a male sibling or direct male relative to perform the test as the pattern of inheritance is similar to any other chromosome: random.
• Mitochondrial DNA testing: In this type of test, the DNA contained in mitochondria is tested to determine the female line ancestry as the mitochondrial DNA is inherited by both males and females from their mother.
• Autosomal DNA testing: This type of test is not limited to lineage alone, and is a broader analysis of your ethnicity. Your autosomal DNA is in the 22 chromosomes that do not determine your sex. You inherit half of your autosomal DNA from your father and mother, quarter from your grandparents, one eighth from great-grandparents and so on. These are the markers that define the physical, mental and ethnic characteristics you have inherited from your ancestors.

Note

You might be familiar with the concept of Gotras. Knowing your gotra is the same as knowing your Y chromosome ancestry, as explained above. Although many people might already be aware, I will provide the explanation in brief to keep everyone’s background information on the same table. All the Gotras are derived from the seven sages (Saptarishi). They are considered to be the forebearers of the male ancestry line. So, our Gotra is nothing but the beginning of the unbroken male-line ancestry. This, along with our mitochondrial DNA is only an indicator to determine who our forefathers were so that we can determine what our mental and physical capabilities will be, based on the autosomal genes we have inherited from them.

So, there is nothing archaic or irrelevant about the Gotra system. It is all science. Related to this topic, two questions come to my mind. First: Are any of the gotras related to each other? Yes, they can definitely be related. For example, Parashara was the grandson of Vashishta, but they are both Gotras. Second: Why are the gotras separate if their Y lineage is the same? This is where the concept of GaNa and Pravara come in. Pravara literally stands for “most excellent” in Sanskrit, which means it identifies particularly excelled sages within a given gotra. I could not find a lot of resources to read about it, but this one article provides a very good explanation to anyone wanting to get a basic idea. Anybody interested in reading more about this can start here. If anybody wants to come up with an explanation or finds more answers, I encourage you to comment and let us all know. There are several schools of thought, but the real question is – how much are you willing to learn, think and grow?

Point to ponder? Stay inspired! Stay Priya-fied!

In the next part, we look at how your DNA and ancestry can affect, build or influence your future. Stay tuned!