(Evangelyn Rodriguez) Humans have 23 pairs of chromosomes, only one of which determines a person’s sex-linked characteristics. The remaining 22 pairs contain bundles of genetic instructions that help determine the other, non-sex-related traits. Since the discovery of DNA, researchers have endeavored to learn all there is to know about these coded sequences, including how much they weigh. The Human Genome Project, which was launched in 1990, provided an answer to this. But in a new study published in the journal Chromosome Research, British researchers discovered that the mass of human chromosomes, which house all of a person’s DNA, far exceeds theoretical values. Even after accounting for all other components (i.e., histone proteins), all 46 chromosomes still weighed considerably more than the DNA they contained.