Based on several details from the original Harry Potter series, Potterheads were able to determine that McGonagall would have been born in the 1930s. J.K. Rowling has never said the exact year McGonagall was born, but fans were able to crack the mystery given how long she has worked at Hogwarts. When questioned by Professor Umbridge in Harry Potter and the Order of the Phoenix, McGonagall says that she had been teaching at the school for 39 years. As the fifth book in the series, that would have been the school year of 1995 to 1996, *quickly pulls up the calculator on iPhone* meaning her first year as a professor would have been 1956. So, how could she have been there for a flashback that took place before 1927? Easy: she couldn’t have.