Some quotes from a recent (2018) article by Sheila Jeffreys, on political lesbianism in the 70s-90s UK and on a book she wrote about it:

Lesbianism and heterosexuality were seen as socially constructed, not innate [by lesbian feminists]. So, hundreds of thousands of women internationally who might not have considered it before and been shaped by all the social pressures to be heterosexual, chose to become lesbians. This mass creation of lesbians was crucial to our politics and to everything we achieved. Now, unfortunately, the idea that lesbianism and heterosexuality, as well as masculinity and femininity are innate and cannot be changed, is fashionable even amongst many younger lesbians who see themselves as feminists. I was involved in lesbian feminism in this period. I made the choice to become a lesbian because of my politics [.......] Most were ‘political lesbians’, in the sense that they became lesbians as a result of their involvement in the WLM and exposure to lesbian feminists and lesbian feminist ideas. This practice of feminists choosing lesbianism as a form of resistance to male supremacy may seem foreign to common notions about lesbianism today, even within feminist circles, which are that lesbianism is something essential, not something that can be chosen [.....] Another chapter of the book is devoted to the crucial critique of heterosexuality which lesbian feminists created, showing that heterosexuality is not an unfortunate effect of nature, but a social construction. [....] Girls are made sexually heterosexual through the sexual attention of boys and men throughout their lives as well as the world of propaganda they are surrounded by, the porn and girls’ and women’s magazines about how to please men in bed and explaining how to do anal sex without too much pain and how to lie on a bed to enable the penis to go right down the throat. Heterosexuality is created by a culture in which all the novels in the airport bookstore are about hets, in which all the movies, plays, poetry, are still overwhelmingly het. And so on. [....] The theorising of sexuality and heterosexuality was the greatest theoretical achievement of lesbian feminism. And a most important aspect of this was the creation of political lesbianism, the idea that women could make a political choice to be lesbians.

Jeffreys is famous for claiming that she ''was once heterosexual, but then chose to be a lesbian''. And she means ''lesbian'' as in homosexual, not celibate. Her view, and as she describes it - the view of the majority of the political lesbians - was and still is that sexuality is a social construct, created through social practices and pressures, and can be changed through the same route.

Edit: Look, I found an ever better quote from her book (parts of it are readable on Google):

Today .. there is much opposition in the online lesbian community to the idea that a woman who has been heterosexual can or should become a lesbian at all. There is a resurgence of the nineteenth-century sexological idea that lesbianism is an innate condition. The understanding that sexuality is not fixed enabled thousands of women to leave heterosexuality at the time of the WLM and become lesbians. As feminist social constructionist influence waned, the biological determinism that was always more favoured by gay men came to prominence again.

Who's a basic bitch now?