Scientists say they have finally assembled the full genetic blueprint for human life, adding the missing pieces to a puzzle nearly completed two decades ago.

An international team described the first-ever sequencing of a complete human genome – the set of instructions to build and sustain a human being – in research published Thursday in the journal Science. The previous effort, celebrated across the world, was incomplete because DNA sequencing technologies of the day weren't able to read certain parts of it. Even after updates, it was missing about 8% of the genome.

"Some of the genes that ma...