This is called “epigenetics”: the altering of the chemistry of individual DNA base pairs without altering the sequence.
It has been known for decades that some traits develop that are not encoded genetically. For example, some reptiles do not have XX and XY chromosomes, and turn male or female depending on whether they developed in an egg close to the center of the next (where it is warm) or closer to the edge.
There are abundant examples of traits that arise from factors other than DNA sequence, which we are only recently beginning to understand.
When I first heard of epigenetics (thank you Jonathan Park) I knew I was toast.