If Shakespeare had a sister who also wanted to write or act, how different would her life be from her brother's?

Very different because it was a sexist society, and women weren't treated equally than men

In the Elizabethan period, only women belonging to the nobility had access to education. Shakespeare’s father was a merchant, and his family did not belong to the noble class. Given the social codes of the time, his sister would have no access to education and, therefore, writing would be out of the question. Acting would not be possible, either, because women were not allowed on stage. She would instead be trained in how to be a good wife, a good cook, and a good mother.

If Shakespeare’s sister wanted to break the mold and pursue her dreams, society would be hostile to her. She likely would not have the support of family members. She also would have been unlikely to find work as an actor in London. In short, it would be nearly impossible for a single woman of Shakespeare’s time to succeed in the male-dominated world of acting and writing.