Sem 2 Genome Chapter 5 Summary: Environment

In chapter 5 of Genome, the tone of the writing changes to cynical.  Ridley explains that the world of genetics is not just black and white.  Genetic inheritance is based on the principles of pleiotropy, pluralism, and the environment of the individual.  The asthma gene exist on chromosome 5 leads to the disorder, but the disorder also has a direct relationship with allergies.  There are many theories on the increase of asthma.  Some believes that pollution from modern synthetic chemicals such as isocyanates, excessive hygiene and others.  The asthma causing gene are the two genes that produce immunoglobulin-E, which comes in different forms and is involved with the release of histamine into the body.  Although asthma has been linked to genes, the genes isolated are trivial and inconclusive.  The cause of the disease is usually attributed most to the environment of the individual.