Is there an indicator of "gayness" in a chart? The quick and short answer is no.
How do you know if someone is gay or not then? Just ask them! Although you may not get a straight answer (pun intended).
However, there are some aspects of a natal chart that suggests that a person may be leaning towards the gay end of the sexuality spectrum. I used the word "spectrum" as I believe most people are not wholly straight or gay. Yes, they may be mostly of a certain orientation but most people aren't 100% straight or gay. This is based on Kinsey's studies. Oh yes, while you are at it, take the Kinsey Scale Test.
Here's some of the aspects of a natal chart which suggests that a person is leaning towards the gay continuum:
- Mars or Venus in Aquarius: Aquarius is progressive. When paired up with Mars or Venus - the planets of sexual attraction, it suggests progressive sexual attitudes.
- Mars or Venus aspects Uranus: Uranus is similar to Aquarius - progressive and inventive. More importantly, Uranus likes to do his/her own thing, regardless of what others think. So, when Mars or Venus, the planets of sexual attraction, aspects Uranus, these people love and make love to those that they desire.
- Moon opposition Venus: Sue Tompkins has noticed this aspect in various homosexual men and women
Notice it's impossible to say that a [fill in your own zodiac sign/Sun sign] is gay. That would be a fallacy indeed.
Explore this subject further with ...