Imagine that you were a parent who puzzled over the mystery of your pre-teen daughter’s hyperactive behavior. Without detailed family medical histories, would anyone recognize this as a preprogammed phenotype?

Could anyone trace the daughter’s behavior back to her maternal great-grandmother being treated with glucocorticoids near the end of the second trimester of carrying her grandfather?

Such was a finding of a 2017 Canadian guinea pig study that was undertaken to better inform physicians of the transgenerationally inherited epigenetic effects of glucocorticoid treatments commonly prescribed during human pregnancies:

“This study presents the first evidence that prenatal treatment with sGC [synthetic glucocorticoid] results in transgenerational paternal transmission of hyperactivity and altered hypothalamic gene expression through three generations of young offspring. Female offspring appear to be more sensitive than male offspring to the programming effects of sGC, which suggests an interaction between sGC and sex hormones or sex-linked genes. Paternal transmission to F₃ strongly implicates epigenetic mechanisms in the process of transmission, and small noncoding RNAs likely play a major role.”

Some details of the study included:

Veh[icle] was the control group initially treated with saline.

The study was informative and conclusive for the aspects studied. From the Methods section:

“Data from same-sex littermates were meaned to prevent litter bias. Sample sizes (N) correspond to independent litters, and not to the total number of offspring across all litters.

Power analyses based on previous studies determined N ≥ 8 sufficient to account for inter-litter variability and detect effects in the tests performed.”

https://www.nature.com/articles/s41598-017-11635-w “Prenatal Glucocorticoid Exposure Modifies Endocrine Function and Behaviour for 3 Generations Following Maternal and Paternal Transmission”