Yes — in the womb
Genes carry chemical tags that act like volume dials, turning a gene's signal up or down without rewriting the DNA itself. Conditions in the womb, such as a mother's diet or stress, can shape these tags on the developing baby, faintly tuning how its genes get read for life. Whether such marks are truly passed further down the line, to grandchildren and beyond, is still debated and unproven in humans.
