In the 19th and 20th century, scientists debated how evolution and speciation could take place. The Darwinian side said it was purely chance-based mutations combined against selective pressures--natural selection. The Lamarckist school suspected this was statistically unlikely and posited that organisms had the ability to pass down acquired traits. They debated fiercely, and the Darwinists declared victory based on Occam's razor because no mechanism was ever discovered whereby acquired traits could be transmitted.
In the 2000s, the U.S. saw some political controversies in which creationists tried to have their anti-evolutionary religious views included in classroom science. The debates around that issue helped solidify a new dichotomy of science vs. religion when it came to the discussion of evolution. During the same era, the study of epigenetics was becoming popular. Owing perhaps due to the aforementioned political discourse of the era, the public at large has allowed epigenetics to be subsumed into the existing theory of evolution as if it is no change at all. From a different perspective (a la the Lamarckists of centuries past,) it represents the possibility of a diametrically opposed paradigm shift.
In these comments there are already comments dismissing epigenetics matter-of-factly as just a part of natural selection. In the purview of scientific history, it's the opposite of natural selection.
To answer your question, the reality is this is very different than what you were taught in the 90s, except that we've rewritten history for science to save face and pretend we knew this all along, and to forget that this sort of thing was explicitly rejected by the Darwinian victors 100 years ago.