The idea that cultural repression of sexuality causes people to be unable to control the expression of their own sexuality is totally flawed.
I think this should be read not especially as 'cultural repression', but as 'group repression'. Because if a person is living in a small, tightly-knit group of people in communal circumstances, that means that everyone will be watching everyone else virtually constantly, with no respite from the spying, tattle-tailing, gossiping and pulling rank/seniority. You probably won't even have any opportunities to express your sexuality in a personal way, meaning you won't be able/allowed to do what you wish sexually (or in other manners either).
That is one of the basic dynamics of communal living, especially if it is hierarchical and/or religious in nature. There is constant surveillance to make sure no one deviates from the accepted group norms and practices. The group ends up controlling you, you do not control yourself or your range of choices anymore,
In any case, I'd like to read more to get a better idea of the story.