Genetically, I have no neck definition. What procedures can counteract this? (photos)

Thank you for your question and for providing a photo. You are likely a candidate for a lower rhytidectomy, also known as a neck lift. This procedure targets the neck and throat directly by removing submental fat and tightening the skin.
The deeper tissues along the jawline are also tightened to create a smooth and defined contour. Results from this surgery can last for well over ten years. I recommend scheduling an in-person consultation with an experienced, board-certified facial plastic surgeon who can assess your situation and suggest the best approach for achieving the definition you’re looking for.

For a more defined jawline to strengthen your profile (and help prevent the dreaded jawline "jowl" sagging), we use injectable fillers like Revanesse Versa - a filler known to limit swelling and give subtle, soft enhancements - or Radiesse. Using a cannula to limit pain and swelling, we inject on the bone in strategic points to get more lift and shaping, resulting in a more contoured lower face and defined, structured jawline. I would suggest getting a formal evaluation with a facial sculpting expert. Best, Dr. Emer

In order to correct position of neck muscles and to address both superficial and deep fat compartments in anterior neck, you will need a neck lift. Only on the basis of in person evaluation one could decide whether neck or lower face/neck lift would be a better solution. Good luck.