What is constellation pairing based on?

In ancient times, people used astrologers to predict people's lives according to astrology. Like tarot cards. Later, with the development of society, fewer and fewer people knew about astrology. The constellations in the sky all have certain shapes, and their shapes are related to large planets such as the sun, the moon and Venus. For example, the sun sets in Gemini Moon Aquarius. Whether people belong to the same genus or not is the basis of constellation matching. Air signs, fire sign and so on.