We understand how sperm “remember” and transmit non-DNA-coded traits to developing organisms.

Despite these impacts not being coded for in the DNA sequences carried by
sperm, studies in mammals have demonstrated that the the’memories’ of
numerous environmental influences, such as nutrition, weight, and stress,
can be passed on from fathers to offspring.

A study from 2021 has provided an answer for how it is possible.

The epigenetics of the story is heavily emphasized. We didn’t know which
molecules that bind to DNA can carry the settings marked by a father’s life
experiences, to be incorporated into an embryo via sperm until 2021. These
molecules can act as on-off switches controlling which DNA sections get
used.