If your parents lead a long life, does that mean you will too? Or, if your parents died at a young age are you genetically doomed to repeat the same fate?
The belief that our expiration date may lay somewhere in our genetic code is one that many people share, and it’s a conversation you’ve probably had with friends or family.
This year, MyHeritage’s Chief Science Officer, Dr. Yaniv Erlich released the results of a ground-breaking study in Science that challenges this notion. The research team, which included scientists at Columbia University, Harvard, MIT and the New York Genome Center downloaded 86 million public family tree profiles from the website Geni.com, which is one of the largest collaborative genealogy websites in the world.
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Once the data was cleaned up, the team had 5.3 million independent family trees to work with. Interestingly, the largest family tree included 11 generations and contained a whopping 13 million individuals! Using this data, the scientists looked at the role of genes in longevity and how families spread out geographically over time.
When it comes to longevity, the research team found that “genetics plays a pretty small role in longevity overall; environmental and lifestyle factors have a bigger impact on how long people live.”
I had the opportunity to ask Dr. Erlich more about the study, here’s what I found out:
A Place for Mom (APFM): According to your paper in Science, your team found that the genetic contribution to longevity was lower than previously thought, “about 16%, which is considerably smaller than the value generally used in the literature of 25%.” You team attributed this difference to the possibility that previous studies have over estimated the heritability of longevity. Were you surprised by this discovery and did the data yield any other surprises about longevity?
Dr. Yaniv Erlich (YE): I was not totally surprised because we knew from previous lines of research that twin studies tend to overstate the heritability of traits. We were pleased to be able to provide a more reliable estimate.
Another finding that was more surprising is the way genes contribute to longevity. There is a long-lasting debate whether each gene contributes independently to a trait or what matters are combinations. You can think about the former model (independent contribution) as a BLT sandwich: you put bacon, lettuce, tomato and feel the bacon, lettuce and tomato. No tomato? No problem. You still get a tasty bacon and lettuce sandwich.
The latter model (combinations) is like making a cake. You take flour, sugar and water and mix them together. You cannot taste individual components and if you take one thing out it is catastrophic for your cake – no water? No cake! We found that in the case of longevity, genes behave according to the BLT model. Each contributes something independently and does not rely on the others.
APFM: In this Atlantic article, you discuss the concept of a genome-wide association study by proxy to help look at genes related to Alzheimer’s. Are there other diseases you’re interested in studying but find it challenging to collect the genetic data you need?
YE: Many diseases can benefit from the genome-wide association by a proxy. Even breast cancer – in normal study designs we can only use the females and the males are largely uninformative. Using our new design, we can also leverage males whose mothers or sisters had breast cancer to find clues about the disease.
APFM: Considering that genes play a smaller role in longevity than previously thought, why is it still important for an individual to know or understand their genetic history?
YE: Genes determines on average only 15% of life expectancy. But there are cases of much more significant involvement. In addition, we can better recognize and prevent certain illnesses. For example, we can reduce the risk of heart disease based on your family history, which will contribute to your life expectancy as well. Finally, the goal is not just life expectancy but also the quality of life.
APFM: Why should people consider adding their family tree or genetic information to a public data set like Geni.com?
YE: Because it is tons of fun and you can make interesting discoveries, such as how you are related to Kevin Bacon, or to any of your favorite public figures or find lost family members, or you can simply learn more about where you come from.
Do you think it’s important to know about your family history? Are you interested in genealogy or longevity? We’d love to hear your thoughts in the comments below.