The phrase "by birth" indicates that someone is born into a certain condition or status. There are a few different synonyms for this phrase, each with their own subtle nuances. One common option is "by nature," which suggests that a characteristic or quality is innate or inherent. "Innate" or "inborn" are also good options that emphasize the natural, unchanging nature of something. Another synonym is "natal," which specifically relates to the time or place of one's birth. "Hereditary" is another useful word, as it suggests that a quality or trait is passed down through family lines. Whatever word you choose, it's important to be clear and precise in your usage so that your meaning is perfectly clear.