There's not even a good definition of what's a lesbian, biologically. There are people who feel they are men trapped in women's bodies. Are they different from women who are bisexual, but prefer women? Is there a difference between butch and fem lesbians? Some of these might be biological traits, and some might be cultural. It's impossible to make a sweeping claim 'this is true of lesbians' unless you figure out exactly what a lesbian is. It's a gender role, not necessarily something biological.
A sample size of 12 is statistically insignificant. If you asked 12 old women and 12 old men if they prefered a certain type of arthritis medication, you could find that 4 women preferred it and 7 men. Does this mean men prefer it more than women or does it mean you didn't test enough people to make any kind of claim?
It's not clear, given the small sample size, that they tested appropriate subjects. It's possible there's a correlation between being openly gay and having lots of sex. In this case, we might say, 'women with an excited libido are irritated by male hormones, while women with a diminished libido are not irritated by it.' This is another reason why three groups of 12 people is too small.
It's a retroactive study. The women were known to be gay or straight before they were tested. There needs to be a follow up study where the subjects are randomized, and the doctors see if the irritating response vs pleasant response is an indicator of sexual preference, not vice-versa.
I could go on.
