Weird to go on a cruise with just my dad and mom when im 19?

So my dad and stepmom invited me to go on a cruise with them. Im not too close with them, theyre kind of weird and he lives out of state.. and normally my 2 sisters (i am very close with) come with me on vacations and im not allowed to bring a friend wither. But my sisters cant come this year, so itd be just me! Im 19 years old, and a little too old to hand out with "daddy" all the time for a week, so do you think i should go stilll tho? I feel like itll be weird to be all by myself on a cruise.. everyone always goes with people..?