I can sew, and I'm actually pretty competent. My mom - who never goes a day without sewing something - taught me. Like your mom, she can see an outfit, go home, make a pattern and whip it right up.
I grew up stuffing dolls and teddy bears that my mom would sew up, and wearing clothing my mom had made from scratch. That was the start. Then in 7th grade, when the styles went from bell bottom jeans to skinnies overnight, my mom refused to buy me new jeans since I hadn't grown much, so I learned quickly how to tailor bell bottoms into skinnies. It's not that hard to do!
Unfortunately, sewing bores me to death. I get bored of the material before I'm finished (even if I finish in a single night). So I haven't sewn anything since the girls were young: back then, I made them all sorts of adorable outfits. Kids clothes are so simple and quick to make.
But, I *hate* doing hems. I send mine out.... even though we have three sewing machines in the house (my old Singer, that I learned on; my DD13's Singer, and my DD15's serger).
My mom taught both my DD's to sew and DD15 has really taken to it. She buys old tee shirts by the pound at this place down town, cuts them up and reconstructs them into minis and dresses and all kinds of stuff. She makes her grandma so proud.
I'm sure I could probably alter my own garments, but over the years, I've developed this aversion to sewing. I do often take clothes to my mom's when I see her and have her make the alterations for me.
Hand-sewing (like buttons) is a different story. I can do it, but I'm not very neat. I did hand-sew a dress once, when I was a teen. I still have it, in fact!! It took forever. I just don't have that sort of patience these days. And I just don't find it fun.