First of all, what is DNA? The letters stand for Deoxyribonucleic acid, a molecule encoding the genetic instructions used in the development and functioning of all known living organisms. Its structure was first described by Nobel Prize winners Crick and Watson in 1953. The information in DNA is stored as a code made up of four chemical bases: adenine (A), guanine (G), cytosine (C), and thymine (T). The DNA bases pair up with each other, A with T and C with G, to form units called base pairs. Each base is also attached to a sugar molecule and a phosphate molecule. Together, a base, sugar, and phosphate are called a nucleotide. Nucleotides are arranged in two long strands that form a spiral called a double helix. The structure of the double helix is somewhat like a ladder, with the base pairs forming the ladder’s rungs and the sugar and phosphate molecules forming the vertical sidepieces of the ladder.
Most of this trait data tells you things you already know, like your hair and eye color, but it is fun to see them compared to your genetic relatives and the world at large. We also found it fascinating to learn more about how these physical traits are genetically determined. For example, finger length ratio is determined by hormonal exposure in the womb, with higher testosterone exposure resulting in a better chance of having a longer ring finger. 23andMe’s Health report for finger length ratio looks at 15 gene markers to estimate your likelihood of having longer ring fingers or index fingers.
It could be that, in the main, genetic-testing kits such as these could, if promoted and used responsibly, end up zoned completely away from legitimate science and medicine and placed where perhaps they belong, firmly in the lifestyle-extra zone, if and when people think they’re “worth it”. Though, somewhat tellingly, when I ask Newman if he thinks that any of the genetic testing kits are worth buying, he instantly says: “No. I’d say, go to the cinema, watch some sport. Spend the money on something nice, something life-enhancing.”
The spit is for one of the home genetic-testing kits I’m sampling. A growing number of these kits (brands such as 23andMe, DNAFit, Thriva, MyHeritage DNA, and Orig3n) promise to unlock the mystery of your genomes, variously explaining everything from ancestry, residual Neanderthal variants, “bioinformatics” for fitness, weight loss and skincare, to more random genetic predispositions, denoting, say, the dimensions of your earlobes or the consistency of your earwax.
Of course, most DNA used by law enforcement in the U.S. does not come from direct-to-consumer DNA tests. The federal government and many states collect DNA samples from suspects of violent crimes after arrest or due to probable cause. These samples are added to the Combined DNA Index System, or CODIS, which is a national database for forensic information.
It is very important that DNA evidence is examined by a suitably experienced and qualified scientist who is able to critically evaluate the DNA results themselves and also to consider their significance in the context of the particular case being considered. This is particularly so in the case of mixed DNA profiles, which may be complex, and in the case of DNA profiles obtained using Low Copy Number or other highly sensitive techniques which may be open to subjective interpretation.
The DNA test thing is a scam as the results cannot have precision. I know where my recent ancestors came from and wanted to “test a DNA test”. My ancestry is 3/4 Spanish Valencian and 1/4 Spanish Ibizean (Ibiza): I have family papers and village names for my recent ancestors: they all have typical Spanish/Catalan names and I expected this to be reflected in my results.
There is one really, really important thing to know about this estimate, however. Each child inherits 50% of their DNA from each parent. That means that 50% of their parents’ DNA does NOT get passed down to the child. This can mean that a child of a 100% Eastern European person will only show 50% Eastern European DNA, and their grandchild will only show 25%, and their great-grandchild 12.5% – in a perfect scenario.
Admixture percentages are one of the biggest reasons people choose to have their DNA tested. This report attempts to accurately match your DNA with population samples from around the world to tell you where your ancestors came from. Each of these companies has strengths and weaknesses when it comes to this calculation, and in the reports it provides to users.
Companies differ in terms of which reference populations they use. Some companies will create their own reference populations, while others will use populations identified in published studies. For example, 23andMe produce their own reference populations by sampling their customers (as long as the grandparents of those customers were all born in the same country). They then combine this data with public population data, produced by projects such as the Human Genome Diversity Project.
My favorite DNA test for finding ethnicity is Ancestry DNA. My second favorite is 23 and Me. The way Ancestry presents their DNA results is easy to understand, and their test is general less expensive than 23 and Me. I have also found Ancestry DNA’s ethnicity estimates very closely represent what I have been able to research the old-fashioned way, both in my family and that of my husband and other family members.
When it comes to proving a biological relationship between a British citizen and a family member living abroad so that they may immigrate, DNA testing can greatly strengthen the case. However, DNA evidence alone does not guarantee a successful immigration application. If you’re considering taking a DNA test for immigration purposes, we recommend you take legal advice to ensure it’s used in the best possible way.
This is another feature of these genetic-testing sites – they are littered with caveats and disclaimers, forever emphasising that they’re not actual “diagnostic tests” and, if you are really concerned by your results, to seek further advice from your GP or another health professional. As has been pointed out by McCartney, when anything looks serious, ultimately it’s back to the very GP and exact NHS infrastructure that these kits profess to smoothly bypass.
DNA profiling can also be useful for those who suspect there may be inheritance disputes over their estate once they have passed away. It provides a record that can be referred to long after someone’s death, even when all physical traces of DNA have gone. Therefore, if there is an unexpected claim for inheritance from an alleged relative, your DNA profile can be compared to that of the claimant to prove or disprove a biological relationship and the inheritance rights.
By comparing the arrangement and distribution of the peaks, it is possible to compare profiles of known origin with a profile from a crime sample. If the two profiles match, databases are used to estimate the probability of obtaining a matching profile from a person selected at random; this is referred to as thematchprobability. Closely related individuals are more likely to share DNA profiles than more distantly related individuals.
This is very interesting…thanks for sharing—regarding you husband’s results– the Somali 1% might not be so crazy at all—look at the map– horn of east Africa to Yemen area (had a large Jewish population long ago)…to Palestine-Israel…to Europe in the centuries long diaspora..actually your comments made me more inclined to try this newer company. I am grateful to you.
Y-DNA Tests: Y-DNA testing examines the Y chromosome passed only from father to son and can therefore be used to gain a better understanding of your paternal line. This can be a very interesting study for those focused on surname research, especially since the Y chromosome can give information about deep and recent roots. Because only men carry this chromosome women will need to test their father, brother or other male relation to use this test for genealogy purposes. Again, FTDNA is the leader in this type of testing and has a wealth of information, groups and forums to help.