From what I understand you can have the vaccine up to age 28 or 29 (I remember thinking I was just past the cutoff.) The reason they don't give it to women older than that is b/c there is a high probability that a sexually active woman has already contracted the HPV virus at some point in time even if she did not know it at the time. As another poster mentioned, kudos to your mom for taking your sister. I am a firm believer in that if there is vaccine that can help reduce the risk of cancer it should be administered to women if they so choose. So regardless of whether or not you are currently or have been sexually active I would say go get your shot.
the tv show the view said its for girls from 9 to 24? close to that. good for your mom to get that for her, too many are afraid it promotes sexual activity. i think maybe if they see they need vaccines for what can happen , maybe they will think about it more before they engage.
women and men of all ages should get it.but it is only approved up to 26 years old.so you still have four years to get it.