11.   Scientist suspect, but have not yet determined, that many of the other early-onset cases are caused by non-inherited mutations in the three genes.

12.   Since the DNA sequence of the two genes differs, it seemed that each would perform a different task in the cell.

13.   Some males of the wasp Nasonia vitripenis, for instance, harbor a mutant gene that destroys all the other genes in the chromosomes.

14.   Surprisingly, the two genes turn out to be involved in the same function, despite their dissimilarities.

15.   The closer the relationship, the more genes are shared and the more similar, for example, the body bouquet of the two parties should be.

16.   The other five genes come in either three or six variants.

17.   The other thousand genes have no match and have unknown roles.

18.   The technique, they say, should help to find several more of the many genes thought to affect human intelligence.

19.   The three genes work as a tightly knit team, together with other tightly knit teams that have yet to be discovered.

20.   The two genes are known to AIDS researchers as Nef and Gag.