You and your sister were adopted by your new mother, and this is the story.
|You and your sister are both anthro red foxes, living in an anthro world|
When you and your sister were born, you were both put up for adoption. You and your sister were quite inseparable, so you were put up for adoption as a pare. Unfortunately not many people wanted to adopt a set of twins. So you both spent most of your child hood in an orphanage.
The orphanage wasn't too bad. It was kinda like being at a elementary school, except you stayed after school to play with the other kids till bed time.
It was a few weeks after your 10th birthday, when a rich woman around 24 years old came into the orphanage. She had recently found out she couldn't have children on her own, so she decided to adopt a kid. She decided she wanted to skip the baby step, and went with a older kid. When she saw you and your sisters profile, she had a little tug on her heart, and adopted you both.
Soon enough, you both move into your new home with your new mother, and have an amazing time growing up.
Its now 6 years later, and your celebrating your mothers 30th birthday. This is where the story starts
You can do pretty much what ever you want in this story, from having zero sex, and keeping it clean. To a full out incestuous love story!
Not many rules other than try to have good writing, and have fun!