Its hard for me to summarize that's why i included the link which is only a summary of the complete study and evidence im sure. But basically what they are saying is you are influenced by your environment and that can influence what is passed down to the next generation and affect their behavior.
Natural selection in each generation, genes undergo random mutations, making offspring subtly different from their parents; those mutations that enhance an organism's abilities to thrive and reproduce in its own particular environment will tend to spread through populations, while those that make successful breeding less likely will eventually peter out.
From two elementary notions random mutation, and the filtering power of the environment have emerged, over millennia, such marvels as eyes, the wings of birds and the human brain.
Yet epigenetics suggests this isn't the whole story. If what happens to you during your lifetime living in a stress can affect how your genes express themselves in future generations, the absolutely simple version of natural selection begins to look questionable. Rather than genes simply "offering up" a random smorgasbord of traits in each new generation, which then either prove suited or unsuited to the environment, it seems that the environment plays a role in creating those traits in future generations, if only in a short-term and reversible way.
There are other implications this brings with a persons behavior as well which can be read in the reference. But basically it is suggesting what we believe about species evolving into better and more complex creatures that adapt well to the environment may not be the only way our genes are affected and what we will pass onto the next generation. The environment around us can have a big affect which goes against evolving into more suitable and adapted creatures and adds other possibilities. It more or less goes against what natural selection says.