This extremely dense and informative 2014 UK summary study provided details about genomic imprinting:
“An unusual epigenetic process in that it is heritable and results in autosomal gene expression according to parent of origin.”
Several notes of interest:
- The term “demethylation” occurred in the study 17 times, and should inform those who argue that epigenetic DNA methylation is a one-way street and not reversible;
- Figure 3 had a fascinating sketch of how the fetus caused the mother’s hypothalamus to:
“Determine forward maternal planning by directing/orchestrating maternal physiology and postnatal maternalism to synchronize with the development of the fetus.”
- Figure 4 followed up with a flowchart of how – with a female fetus – the coexistence of three matrilineal generations in the pregnant female (her, the fetus, and the grandmother’s influence on the developing fetus’ ovarian oocytes) enabled transgenerational forward planning.
- The study briefly noted the significance of genomic imprinting on male sexual behavior, where, if the processes didn’t proceed normally at this early stage of the male fetus’ development, could result in suboptimal adult behavior that didn’t change with experience.
I’ll quote a few other unrelated passages that caught my eye.
“The reproductive success of mammals also places a considerable burden on matrilineal time and energy, with some 95% of mammalian female adult life committed to pregnancy, lactation, and maternal care.
Thus, offspring that receive optimal nourishment and improved maternal care will be predisposed to develop a hypothalamus that is both genetically and epigenetically predisposed to this same type of good mothering.
Thus, the fetus controls its own destiny in times of acute starvation, especially in the last trimester of pregnancy, by short-term sacrifice of its placenta to preserve resources critical for brain development.”
http://www.pnas.org/content/112/22/6834.full “Genomic imprinting, action, and interaction of maternal and fetal genomes”