Sewing.
I so wish that I could sew.
I have never been very skilled with a thread and a needle. This has been my curse ever since I took Home Economics in high school. For the sewing semester, we got to choose a stuffed animal to sew and stuff and take home. I had decided that I would make this fluffy white kitty cat to give to my younger sister. It looked like a cat. But it wasn't pretty... I felt bad for that kitty. And for my sister. ;p
My mom is a sewing whiz. She always made my sister and I's Halloween costumes, and they were often unique and very detailed. She sewed baby doll clothes for our Cabbage Patch dolls. She has hemmed almost every pair of my pants & jeans that were much too long for my 5'1" frame. My mother even hemmed my wedding gown, removed the train that I didn't really care for, and then used the material from that discarded train to make me a matching bolero jacket...
My sister can knit and make beautiful hats and scarves. But me? De nada. No crafty needle skills whatsoever.
The sewing gene obviously skipped me in my family.
What is one skill that you wish that you had?