Kastor

Kastor is a Greek masculine name, and a direct descendant of Castor, one of the heavenly twins of Greek myth immortalized in Gemini's constellation. Castor and his brother Pollux are twin half-brothers, only one of which is immortal, with the word "twin" doing some heavy and confusing lifting there. Meaning "beaver," baby Kastor may be cautious and risk-averse, preferring to follow established procedures rather than taking chances. Beavers are also known for their analytical skills and ability to organize complex information, so maybe Kastor can explain the term "twin half-brothers."