Sarah was born in 1993, as evidenced by this passage: "In 2023, Sarah celebrated her 30th birthday with a big party." 30 years ago from 2023 is 1993, the year Sarah was born. Her younger sister being 5 years younger and studying abroad means she must be around 25-26 years old. This would make sense for the age difference between two sisters, with Sarah at 30 and her sis at 25. The study abroad detail is a red herring not relevant to determining Sarah's birth year. Therefore, the year Sarah was born is 1993.<|end_header_id|>