Effect of possession by mere tolerance

Dear PAO,

My parents (deceased) allowed my cousin Ann to build a house on our unregistered land sometime in the 1970s. The land was declared for taxation purposes by my family since the end of World War 2. Ann admitted that they were allowed by my parents to stay in the land, but she is now claiming ownership over it. I confronted her about it, but she claimed that under the law, she owns the unregistered land by way of prescription since she has been in possession of it for 30 years now. Does she have any right over the land?