Perhaps you should look harder at the kind of upbringing your family members were indulged with. I also have a number of ‘cousins’ as you refer to them. I am not sure of the exact usage of your verbage, but will accept ‘cousins’.
I was raised in a household where there were a number of guns. Rifles, shotguns, other combinations of same & handguns.
While we certainly did not have an ‘Ozzie & Harriet’ upbringing there NEVER was one single thought that using a gun or grabbing a gun as a threat was acceptable. As we grew older, guns were used by every child raised in that family.
A GUN is an INANIMATE object. You may have to have someone explain that definition to you.
A gun doesn’t do any harm all by itself. It can actually be owned for many years by someone & never have any kind of problem with it’s usage!!! Surprise!
Nobody did a single thing about banning Oldsmobiles when Teddy Kennedy tried to test his ability to drive while intoxicated & killed his passenger....
You are on the wrong path towards a solution to gun violence.
Your solution starts with proper discipline in the home & in the schools, IMO. Since your ‘cousin’ is now not a threat to others of us who can behave in society, we all can sleep a little better, also.
If you look at the person committing the act as the independent variable, you have to start asking some hard questions. Questions that lead to places most today don't want to admit to, so it is easier to blame the object.
That is why we have such things as gun control and soda bans. We, as a society, refuse to hold people responsible for the choices they make. We wish to be children forever.