When I was a kid, yes, I could sing. I was in a city choir when I was about 9 or so, which of course you had to prove you could sing to be let in. I was eventually kicked out due to the fact that I had self control issues, mainly due to manic episodes.
Several factors, like having gone through puberty (yes, girls' voices change a bit, too), and being out of practice (though I sing along to my music a lot when I'm alone), contribute to the fact that I can't really sing too well anymore. My voice sounds rather weak and off key, and I can't hit high notes at all despite having been a soprano singer when I was in the aforementioned choir.