There are two factions of lesbians. It can get confusing.
One faction is political lesbians and supporters of it. It's authentic 1970s radical feminism. The theory goes that all people are attracted to women as a baseline, and that you can rediscover it at some point by undoing the brainwashing of compulsory heterosexuality. Most of these are older women who saw a shift towards lesbian relationships happen in their communities in the same time frame as feminism gained popularity. They make it seem like anyone can be a lesbian if they try hard enough. If you dislike the denigration of your attention to men you're supposed to try women.
The others are born-that-wayers, who hate political lesbianism, tend to be young people. The born that way lesbians expect heterosexual and bisexual women to not complain about being denigrated all the time in feminist activist circles. They also have a huge problem with interrogating each other for the crime of fake lesbianism or even support of political lesbianism. The dirt from dirt is one of those, to a truly deranged degree, she cranks out countless blog posts about the evils of fake lesbians.
The complicated part is that a lot of women who come out later in life don't describe themselves as having always been lesbians, they stopped being attracted to men and became attracted to women, lots of times after having been married and raising kids with a man. I don't think they are mistaken about who they were attracted to. the other thing that complicates the argument is how many women try to be gay and ultimately dislike it. No one is really "right" about if you must be born that way because it appears to work that way for some women but not others. Born that way definitely seems to describe male sexuality.