I would like to ask how to interpret the poem by Jackie Kay "We are not all sisters under the same moon" especially the title.

I haven't read the poem, I have to admit, but I still
believe that I might be able to say something about what the title might
suggest.

To me, the title seems to go against the popular
notion that all women share basic things in common and thus are naturally friends,
allies, or "sisters." This popular notion is often called, often
disparagingly, "essentialism" or "radical feminisim." The reference to the moon in the
title is telling, I think, as it evokes the whole notion of the 28-day (or so) lunar
cycle; the moon often functions in literature as a symbol of the feminine, probably in
part because the lunar cycle seems to coincide with the menstrual cycle for many women.
("Coincide" in the sense that the average menstrual cycle tends to be about 28 days, not
in the sense that the moon is in any way involved in the menstrual cycle. "Under the
same moon," now that I think about it, may even be hinting at the idea of women's cycles
'synching up" if they're around each other a lot.)

Critics
of radical feminism often point to how women are not a single, unified group. There are
profound differences of race, class, sexuality, nationality, ethnicity, etc. The idea
that all women are "sisters" may be appealing to some, but others see it as a myth that
obscures the real differences in power and status that different women
experience.