I remember there was an experiment with mice about genetics and scents. The first generation mice were exposed to the scent of cherry blossoms whenever they received a painful shock, so they became conditioned to be afraid of the scent. The thing is that the second and third generation after that, never received the shock, but was still terrified at their first whiff of the cherry blossom scent. Here's a newspaper article about it https://www.washingtonpost.com/natio...fac_story.html

So to me it's possible that something similar happened with the scent of the ASFs except this time encouraging a feeding response.