Xavier Remington 
One or both of your parents probably decided to leave Atlantis, Neptunus, or Pacifica which are the main Mermaid civilizations. When a Mermaid decides to leave the sea, and live in the human world it’s usually for love so most likely only one of your parents is a Mermaid. Mermaid civilizations are ruled by royals, and are very controlling. They don’t like it when their citizens leave. They will either shun them forever, or hunt them down depending on the impact they had on the Mermaid society.
Naturally one or both of your parents love the sea but want to appear human so as not to get on the radar of Mermaid enforcers. A Mermaid can grow legs on the night of a full moon. They will return to Mermaid form on the night of the next New Moon. If the full moon falls on Halloween then the transformation is permanent. One or both of your parents must have done that or had some magical intervention. Depending on your parentage you might transform in sea water if you stay in a certain length of time. They also might be concerned that Mermaids will kidnap you as leverage to make your parents return to the under sea civilization.
Of course there’s another possibility. You might be adopted and there was some danger your biological mom or dad was facing, and they brought you to a beach on the night of a full moon when you were just born. Freshly born Mermaid babies can be permanently transformed to a human like state by any full moon. Your adoptive parents might have been there for whatever reason, and took possession of you.
Learn More About Mermaids At: http://mysticinvestigations.com/supernatural-beings/mermaids.htm
