I just realized... if the queen of Corona (Rapunzel's kingdom) and the former queen of Arendelle were in fact sisters, as is the common theory, then Elsa and Rapunzel would be essentially the exact same age! Rapunzel was 18 at the end of her movie, which was 3 years ago. 18+3=21. Elsa is 21 in Frozen, this year. These two really need to get together. They would get along so well! Best cousins ever!