Scientists have sequenced nearly half a million human genomes and attempted to answer a long-standing question: how well can we explain the heritability of various human traits if we examine DNA as deeply as possible? In the past, geneticists often spoke of the “missing heritability” — the portion that could not be detected through conventional genetic studies. A new study published in Nature shows that with complete genome sequencing, this mystery is beginning to clear up.

The researchers analyzed data from 347,000 people and examined more than 40 million DNA sites — from the most common variants to extremely rare ones. They found that when all these differences are combined, roughly 88% of the heritable contribution to human traits can be explained. This is a major breakthrough: previously, many believed that rare variants were nearly impossible to detect statistically, but it turned out that they account for about one-fifth of all heritability.

Interestingly, even tiny, rare DNA changes that occur in less than one percent of people play an important role. Some of these changes are located in the genome’s “coding” regions — the ones responsible for producing proteins. Although such regions make up less than 1% of all DNA, their contribution to heritability proved unexpectedly large. But non-coding regions, once considered “quiet” or secondary, also have an impact — their effects are simply more complex and subtle, yet significant in total.

Some traits, such as height, can now be almost fully explained using whole-genome sequencing data. Others, like the number of children a person has or telomere length, still retain gaps. These may be influenced by even rarer or more complex variants that remain difficult to detect.

The scientists also identified thousands of new genetic associations, especially those related to cholesterol levels and other health indicators. In the future, this may help improve risk prediction and deepen our understanding of which characteristics of the human body are genetically determined.