Could upper arm fat be genetic?

I've been doing CKD now for about 4-5 months, and i'm down to just around 10% bodyfat according to my calipers test. Now I know that being in keto makes one look really small and flat, but my shoulders just still don't look defined hardly at all. I know that I haven't lost much muscle bc I have kept all of my strength, but I still have that patch of skin right around my rear delt and upper tricep. I just want nice defined shoulders like Dwight Howard or Lebron, but could that just be genetics? I have strong shoulders, and I've hit them from every which way, but my rear delts have always lagged behind, while my triceps have always been large. Could I just be genetically predisposed to holding onto fat in that area? Does that mean that I'd have to get down to really low bf% to see it gone? Like 6-7%? I fear that if I did that I'd most likely loose muscle going that low, but i've always wanted good shoulder definition. So would I have to go really really low to get that, or would it be that same that low?

i'm not an expert or anything, but i am a college kinesiology student, and your question doesn't have many answers so far so i might as well answer....

I've read that fat storage patterns are genetic. That being said, the shoulders don't really bulge out when you're just standing there with your hands at your sides (unless you've got a ****load of excess muscle). So you probably are building shoulder muscle, you just don't notice. Try lifting your arms straight in front of you or straight at your sides, and see if you have any definition in the shoulder.