That said (shy of falsely imprisoning or securing chastity equipment), while family cannot stop a minor who is legally capable of giving consent from doing so, the legal guardian of a minor can seek protection from the Court on the minor's behalf and against the minor's will in the form of a restraining order / injunction for protection.
Similarly, if you are able to consent (if you are 16 or 17) but you have sexual relations with someone who is either 24 or older or younger than 16, then your consent is similarly legally insufficient and will not be a factor in an ensuing criminal prosecution. If you are younger than 16 then your consent, no matter how heartfelt, is legally insufficient and will not be a factor in an ensuing criminal prosecution. In Florida a 16 or 17 y/o can, legally / lawfully, consent to sexual relations with someone who is 23 or younger.