Combine the plots of the last two movies you watched

Beautiful Kate (2009) + The Shape of Water (2017) = The Beautiful Kate of Water.

At a top secret research facility in the 1960s, a lonely amphibian man (Doug Jones) starts having memories of his beautiful twin sister, Kate (Sophie Lowe), and himself when they were younger. These memories awaken long-buried secrets of brother/sister fish sex from the family's past.