Two things will help researchers discover the genetic factors behind those traits we see shared in families. First, studies that include a very large number of people with and without a given trait will help us find common genetic factors that have even a small influence on the trait. By involving tens of thousands of people in studies, researchers have recently discovered genetic variants that influence freckling, sneezing in bright sunlight, and whether or not someone has a sweet tooth.Second, a trait such as the love of vinegar and lemons that you share with your cousin may be influenced by genetic variants that are unique to your extended family. In that case full genome sequencing — that is, examination of all 3 billion positions in the genomes of a few family members — would be needed to get to the bottom of the family mystery.DNA can tell us a lot about our ancestors and where we came from, and it turns out that it can also tell us a bit about why we’re the way we are. Perhaps that trait you share with someone in your family tree comes from a little shared DNA.
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