According to this answer on Quora.com:
In the astrological context, which determines a person’s character, everyone born under the rising signs (lagna) of Gemini, Libra and Aquarius is characterized as Shudra. A Shudra in this context is one who is content to work for others, has little ambition, is subjected to passions, lacks an efficient method of self-control and primarily follows their biological programming of self-preservation and self-propagation.
Is the same mentioned in any jyotiṣa-related scripture?