Nova has already had a very good episode on the field of epigenetics:

http://www.pbs.org/wgbh/nova/genes/

The most remarkable concept in this field is that it is possible to INHERIT epigenetic traits from your parents or grandparents that they developed only in their lifetime.

It also brings into focus the dangers of chemicals like pesticides, in that they are often chemicals that cause DNA methylation. Thus it could be possible to pick up genetic problems from eating pesticides, then pass those problems along to your children and grandchildren.