Sharing Sucks

I hate to share.  I am fine with giving, or volunteering, or donating, but I can't stand having to share something that is unequivocally mine.  My car, my clothes, my computer - I'm not fond of taking turns with any of it.  I guess my attitude comes from never having anything to truly call "mine".  Growing up, my family was pretty solidly middle class, so it was never a matter of money...more like a matter of logic.  I have an older sister and a handful of female cousins who always grew quicker than I did.  So, my new clothes and shoes were hand-me-downs, as well as my toys, roller skates, and bikes.  I didn't care as long as they still fit/worked/rolled.  I used them proudly and sent them on to their next owner.  But as I got older my desire for non-previously owned merchandise grew, and I began to save my money.  My first real purchase was a $99 white metal daybed; I was so proud to plunk down a wad of cash made from my allowances, Christmas and birthday presents, and rewards from a school year of straight As.  My bed was mine.  I could honestly appreciate the fruits of my labor.  It shouldn't be a surprise when you fast forward to today and I'm holding onto my car keys and my computer password with the kung-fu grip.  I can't stand sharing, but I'm not a complete hard ass.  My kids have their own username on my computer; my husband has a key to my car.  I simply don't like to give up my things without a fight or at least a promise in blood that they'll come back relatively close to the way they left my possession.  I don't think that's a horrible thing to ask.  Do you?