Final answer:
The 23rd chromosome combination most likely to result in a person with both male and female traits is XXY, characteristic of Klinefelter syndrome.
Step-by-step explanation:
The 23rd chromosome combination that is likeliest to result in a person with male and female traits is XXY, which corresponds to one type of Klinefelter syndrome. Individuals with Klinefelter syndrome are genetically male, with the presence of a Y chromosome, but they exhibit some physical traits often associated with females due to the additional X chromosome, such as small testes, enlarged breasts, and reduced body hair. The extra X chromosome in these individuals undergoes inactivation, known as Barr body formation, to compensate for the excess genetic dosage.