"The age of consent is 16 for male-female sex if both individuals are emancipated. It is 18 if the individual is not emancipated. The twins being 17 and living at home are not emancipated."
The only statute I could find went as follows:
IV. Engages in sexual contact with the person when the actor is in a position of authority over the person and uses that authority to coerce the victim to submit under any of the following circumstances:
(a) When the actor has supervisory authority over the victim by virtue of the victim being incarcerated in a correctional
institution or juvenile detention facility; or
(b) When a probation or parole officer has supervisory authority over the victim while the victim is on parole or probation or under juvenile probation.
Source. 1975, 302:1. 1981, 415:4. 1985, 228:4, eff. Jan. 1, 1986. 1997,
220:3, eff. Jan. 1, 1998.
This statute doesn't support your position. Perhaps there is another that I can't find.