Szyf – intergenerational epigenetic changes – two mechanisms

There is some evidence that epigenetic marks can pass down the generations. And there are two really mechanisms how it can work. One mechanism is behavioural inheritance. For example, rats that were low licked by their mothers will become low licker mothers, and we know there are epigenetic marks that go with it. These marks are not inherited by the sperm or the egg, they’re inherited through the behaviour of the mother. So we believe that certain behaviours are inheritable through the behaviours of the caregivers or the environment. They will stay for generations causing marks not in the germ line but the behaviour of the environment.  

There are other kind of marks that don’t require the presence of the caretaker but are mediated through the germ line. So it is possible to change not only the DNA methylation marks in the brain, but also DNA methylation marks in sperm. The big question is whether stress can cause changes in methylation marks in sperm. One can think about ways that that can work through hormones that can go from the brain to the sperm, to the testes, and then this is passed to the next generation, and because these marks have a property, they can be propagated, they can be replicated. That can now be passed to different tissues, and remain in different tissues. This is a way by which one generation can send information on experiences to the other generation.