1.   Rothenbuhler thought that hygienic behaviour might be controlled by two recessive genes.

2.   The build-up of recessive genes increases the incidence of genetically determined diseases, such as sickle-cell anaemia in humans.

3.   There is a recessive black gene in the breed as well.

4.   Sickle-cell anaemia is passed on through a recessive gene.

5.   However, if you get two copies of a recessive gene from both parents, then the recessive gene will be expressed.

6.   On the other hand, the estimates from siblings may be inflated because of within generation environmental effects or the influence of recessive genes.

7.   Albinism comes from a recessive gene and must be inherited from both parents.

8.   By mating the unusual mouse with littermates carrying a recessive gene for the same trait, Jackson began developing genetically pure mutant strains.

9.   Coded by a recessive gene, meaning that one can be a silent carrier, the actual disease requires both parents to have the trait.

10.   Cystic fibrosis and Tay-Sachs disease, for example, are caused by recessive genes.