It's legal

[Dragon_Master]

In your family it's you age 19 twin sisters age 18 mom age 37 and dad age 39

You heard on the news that incest is now legal and went to tell your mom she was to happy with it when you mention maybe one of your sisters would want to have sex caused mom to tell you she'd rather you fuck her instead of one of your sisters not long after you and mom found out your sisters started having a lesbian relationship with each other 

Any thing else is up to you