Now here's a frightening thought! Brain chemicals such as endorphins, and drugs, such as marijuana and heroin are known to have significant effects on sperm and eggs, altering the patterns of genes that are active in them. In an article published in the latest issue of the journal Bioscience Hypotheses, Dr Alberto Halabe Bucay of Research Center Halabe and Darwich, Mexico, suggested that the hormones and chemicals resulting from happiness, depression and other mental states can affect our eggs and sperm, resulting in lasting changes in our children at the time of their conception. Bucay suggests that a wide range of chemicals that our brain generates when we are in different moods could affect ‘germ cells’ (eggs and sperm), the cells that ultimately produce the next generation. Such natural chemicals could affect the way that specific genes are expressed in the germ cells, and hence how a child develops.