Humans are 99.9 percent genetically identical and have only twice as many genes as the worm or the fly, according to information released yesterday by organizations that are sequencing the human genome.

Two separate reports by rival organizations--the International Human Genome Sequencing Consortium and Celera Genomics-- were released after many months of intense investigation and are already overturning some longstanding beliefs about human biology.

The full results, to be published in journals later this week, reveal that the actual number of human genes--about 30,000--is much smaller than previous estimates.

Information released yesterday also showed the following:

* In comparison to the genomes of other organisms, human genes tend to be distributed in clumps, with coded genes close together and long stretches of non-coding "junk" DNA;

*More than 200 genes in the human genome are most closely related to bacteria;

*The human genome has a larger percentage of junk DNA (50 percent) than the genomes of the mustard weed (11 percent) or the worm (7 percent);

*The ratio of mutations in males versus females is two to one. This may possibly be linked to the greater number of cell divisions involved in sperm formation versus egg formation.