I'm pretty fucking sure your fingers don't base your sexuality. That's just ridiculous. Get a grip.
It doesn’t “base it,” but it’s well documented that it’s correlated with it, especially in women, likely due to prenatal androgen exposure. A woman who is attracted to women is more likely to have a low digit ratio than a similar woman attracted to men.
And besides, potential evidence for biological markers of sexuality actually tends to promote lgbq+ rights. There’s no need to be so rude. ¯\_(ツ)_/¯