Tonight is a special night. It's your 18th birthday at midnight, meaning you will now be officially considered as an adult. But the thing about this town you luve in, is that upon everyone's 18th birthday, the moment the clock strikes midnight, they undergo a vast transformation. Most of the time, it is just the person getting a bit taller, stronger, etc. in other words, just an enhancement of their already pre-existing features. But sometimes, a person can become someone, or something else entirely. They could be turned into an animal, the opposite gender, part object with the ability to function like a living being and that object, etc. And to top it off, they will all have to live with it until they die.
With just 10 seconds until midnight, you are waiting nervously for your own transformation to begin. Both your parents and a few other of the town members who happened to be up at this hour were all watching. If the pattern for your family persisted with you, then you should just get a great physical enhancement, become even more good looking than you are now, be more in shape, and overall come out an even better person than you were when you went in. Both of your older sisters became gorgeous women with one of them even gaining a high aptitude for magic when her constitution was improved. Your parents are both amazing people with great looks and amazing bodies. The last time any of them got sick was back before their 18th birthday.
And now it's finally your turn for a glow up, hopefully. The clock strikes midnight and you become surrounded by a blinding light in an instant, signaling the start of your transformation...