The Mind-Blowing Science Behind Intergenerational Trauma
Posted on August 19, 2016
Okay friends, let’s get our nerd on for a moment and look at some of the amazing, and in many ways devastating, science behind intergenerational trauma. To try to make this as simple as possible, I’m going to bullet point what I believe are the key findings, as they speak for themselves. To begin with, here is the evolving research with human subjects:
- Let’s first get clear about two types of DNA:
- Chromosomal DNA (or what most of us just think of as DNA): Transmits physical traits such of color of hair and skin. Chromosomal DNA makes up 2% of our total DNA.
- Noncoding DNA: Responsible for the genetic expression that makes up our personality and emotional, behavioral, and social traits. There are many ways for the noncoding DNA can be expressed. For example, we are all born with some level of musical potential. If we are born into a family with musical parents, we would likely express our genetic musical genetic potential. If born into a home without instruments or musical parents, then this genetic potential would not be realized. Some might have a higher genetic potential than others, but the environment will be highly influential in how this is expressed. Noncoding DNA increases with the complexity of the organism (humans have the greatest amount of noncoding DNA than any other animal) and accounts for 98% of our DNA. When I say “DNA” or “genetic expression,” this is the type of DNA I’m referring to. Noncoding DNA expression can be greatly influenced by trauma, leading to changes in personality and brain functioning.
- Trauma can alter cortisol levels, which has been demonstrated to increase likelihood for Post-Traumatic Stress Disorder, depression, anxiety, numbness, insomnia, frightening thoughts, and being easily startled or on edge. Genetic expression tilts towards survival systems at the expense of emotional regulation and higher-level thinking processes.
- Studies led by Rachel Yehuda have shown that those who have experienced intense and/or repeated trauma can pass this cortisol condition and genetic expression on to their children (who have not experienced trauma directly in their own lives).
- Generational DNA Expression:
- Maternal Influence: The egg that created you was created when your grandmother was 5 months pregnant with your mother. For a few months, three generations share the same biological environment. The genes that your grandmother needed to survive or thrive in her environment are passed to your mother and, in a lesser but still significant way, to you.
- Paternal Influence: The precursor cells for sperm were developed similarly to the process of the egg described above. However, sperm continues to multiply and be created throughout life. Therefore, the genetic makeup of sperm is influenced by events that happen throughout the father’s life, almost to the point of conception.
- Impact of mother’s state on developing fetus:
- DNA expression can be impacted by our positive and negative feelings, thoughts, and beliefs about the world (i.e. Personal Narratives). A mother’s fear, anger, love, joy, and other intense emotions create a biological state in the mother’s body that corresponds to each of these emotions. This chemical reality is passed by the mother to the child through the placenta wall.
- Bruce Lipton: “When stress hormones cross the [human] placenta . . . they cause fetal blood vessels to be more constricted in the viscera, sending more blood to the periphery, preparing the fetus for a fight/flight behavioral response.”
- Impact of mother’s stress and trauma on the child:
- Impaired cognitive development
- Premature birth
- Lower than average weight
- Irritable and colicky
I want to stop here for this week and we’ll look at some animal studies next week. I hope this helps set the framework for the power of intergenerational trauma. When I started to think about how grandmother, mother, and child all inhabit the same biological environment, it really reinforced how trauma can reach out across generations, and how many struggles our clients have that are not just their own, but also the struggles of their ancestors. I want to open the comment section up this week for your reaction to their research. I have much more to say on this issue, but I’d love to hear what you are thinking after this brief introduction.
A few quick notes:
- Just want to recognize Mark Wolynn, whose book It Didn’t Start with You provides the best scientific summary on this topic and is now on our must-read list! The scientific references in this post are from his book, and I will pull heavily from that book for this series.
- This research is evolving quickly in both human and animal studies. Five years from now, we’ll know significantly more, but even now, there are strong findings that are starting to shed light on where we are going.