I wish I could say it was my dad or my grandfather, but not really (at least not directly). My father and mother are strong antis when it comes to guns. Dad grew up in rural western PA, in a family where some days, if they didn't get anything when they went hunting, they didn't eat meat. Between that (guns were practical and not recreational) and becoming extremely liberal after college, and he hates guns.
Growing up, my grandfather had a wooden locking gun rack bolted to his wall that I'd often eye when we went to visit:
View attachment 1157615
(Not his, but very much like this)
One day when I was 5 or 6 he showed me (and let me handle) a .22 rifle and a .22/20ga over/under and one of my parents (I can't remember if it was my mother or father) totally chewed him out for it. From then on, I could look, but he never let me touch them, let alone taking me out shooting as I got older.
I was interested in guns from high school on. The first time I shot was basic training. Initially, I couldn't even successfully zero my M16, but one of the Drill Sergeants on the range (not from my company) took some time and 1 on 1 taught me how to shoot. That was an important step, and I quickly got pretty good (in the days leading to qualification I would be right on the line between Sharpshooter and Expert when practicing, unfortunately, when we qualified I shot Sharpshooter, just barely missed Expert). Almost a decade later, a friend bought a handgun, and several of us started joining him at the range (I sometimes shot his gun, and often rented a revolver). My next influence was Chuck Taylor, I read his paperback The Gun Digest Book of Combat Handgunnery (4th Edition) so much I wore it out and had to buy a second.
View attachment 1157616
Since then, I've participated in a number of training classes. I watch YouTube videos of a number of trainers and experts. Probably the one I give the most weight would be Mas Ayoob, and of course any online tips from Jerry Miculek's articles and videos, but at this point, I'm not sure how much "influence" I'd say any of them have on me. I pay attention to what they have to say and use what I can, but I don't necessarily weigh any one more heavily than the others.