Learning to become afraid and passing it to children

Animals can pass on information about a traumatic experience to their offsprings. Researchers at Yerkes National Primate Research Center, Emory University have found that when a mouse learns to become afraid of a certain odor, his or her pups will be more sensitive to that odor, even though the pups have never encountered it. This is an example of an "epigenetic" alteration: transmitted not in the letter-by-letter sequence of the DNA, but in its packaging or chemical modifications.

In mice taught to fear cherry-blossom-smelling chemical
acetophenone, the odorant receptor gene that responds to this compound has a changed pattern of methylation while 
the sequence of the gene encoding the receptor that responds to the odor remained unchanged. And it's all because DNA from the sperm of smell-sensitized mice is altered. As senior author of the study Kerry Ressler says. "There is some evidence that some of the generalized effects of diet and hormone changes, as well as trauma, can be transmitted epigenetically."