Genetics is the passing on of characteristics from one generation to the next. The process of genetics occurs among all living things, including animals, plants, bacteria, and fungi. Genetics are molecules called Deoxyribonucleic Acid (DNA). DNA is a necessary molecule that is apparent in all living things.
Genetically-inherited diseases are diseases that are passed down through generations within your family. These diseases are specifically transferred through the genes in our DNA, passed down by carriers of mutated and defective genes. It is important to be aware and understand that you may be at a higher risk for some health problems because of your genetics due to your family history so you can take precautionary measures.
Siblings share, on average, about half of their DNA. The reality is, however, we can be anywhere from 0–100% genetically related to our siblings! When looking at DNA test results, you could, theoretically, be unrelated to a sibling, though the percentage usually falls in the 50% range.
Your ethnicity results found in an Autosomal DNA (atDNA) test can be quite different from sibling to sibling, as we each inherit unique combinations of DNA from our parents that present different parts of our genetic history.
This stems from how DNA is passed from one generation to the next for the majority of our genome. You are unique, having received 50% your DNA from each of your parents. Your parents received 50% from each of their parents, and so on. The 50% passed to you from each of your parents was a shuffled combination of genetics, so unless you and a sibling are identical twins, you can expect your results to be different than your siblings. Recombination is purely random, so one sibling could inherit substantial chunks of DNA that the other sibling did not inherit—or vice versa. Sometimes, the differences in results can be surprising.
ANCIENT VIRUSES HIDDEN IN YOUR DNA FIGHT OFF NEW VIRUSES
THE HUMAN GENOME is three billion letters long. About 240 million letters of it, scientists estimate, is viral. Eight percent of human DNA comes from ancient viruses that once infected our ancestors. Most viral infections are as fleeting as a cold, but two things made the ancient ones unusual:
- These viruses had the special ability to copy themselves into the DNA of their hosts.
- They sometimes got lucky enough to copy themselves into an egg that became fertilized and grew into a full-fledged adult. So that viral DNA got passed down from generation to human generation as so-called endogenous retroviruses.
Some of it may even make you, you. As a growing fetus, you co-opted a gene from an ancient virus to form the placenta that kept you nourished in the womb. And in recent years, scientists poring over gigabytes of genetic sequencing data have seen other tantalizing hints of endogenous retroviruses turning useful. Science suggests humans have also co-opted the remnants of ancient viruses to direct the immune system against other pathogens.
I have learned so much about Genetics and Heredity, that I want to learn more! If you feel the same way, consider visiting the DNA Learning Center at www.dnalc.org.
