Sooo, it turns out that Kate Middleton laid out some strict ground rules before agreeing to marry Prince William and officially join the royal family.

According to a new biography from Robert Jobson (via Us Weekly), the Princess of Wales “established some fundamental life rules that she would stick to when she joined The Firm. Her ‘terms’ were in fact presented to Queen Elizabeth and Prince Charles…She was clear from the outset that she would not be pigeon-holed into carrying out particular duties…her priority, she emphasized, would always be her family.”

Kate is known for being an extremely present mom to her three kids (Prince George, Princess Charlotte, and Prince Louis), but—along with doing a ton of royal engagements—she’s apparently had a big influence on the monarchy/how it functions.

“Kate will be very important in shaping the monarchy into an institution that’s relevant to modern people and not just looking over its shoulder at past traditions,” Jobson writes. “She’s a really stylish, incredibly graceful and beautiful lady, but she’s got a steely core, and that enables her to say what she believes. She’s not afraid of giving her input and she influences a lot of people that make the decisions.”

FYI, Kate is currently taking a break from royal duties as she goes through preventative chemotherapy, although she *has* made a few public appearances this summer, most recently at the Wimbledon men’s finals. More on that…