The sex in space issue
Frankly, even if there were women on board, the sex issue won't come up....
It's all a matter of all kinds of incentives, publicity, social urges here on Earth.
Once in space, all by themselves, they won't be affected or encouraged by all the hooplah over here. They'll be affected by weightlessness, training for the mission, following orders, having the best conduct towards each other, doing their job.
Volunteers, isolated, have demonstrated that they didn't necessarily need sex to spend their time in isolation.
That "sex" stuff is only something that sells...not in space, but here on Earth.
Raoul