Genetics: Haemophilia YouTube activity This worksheet accompanies the first 15 minutes of a YouTube video called 'Haemophilia and Porphyria: Royal Diseases from tainted Blood': https://www.youtube.com/watch?v=bmQwMllhCUM The video clearly outlines how the X-linked disease has traveled from Queen Victoria, a carrier, through many Royal European bloodlines. While watching the video, students have to discuss and answer questions about x-linked crossesin real-life, historical situations and they have to draw up punnet squares to support their answers. The historical context ads an extra layer of interest in the subject of genetic crosses and x-linked inheritance specifically. My students loved to do this worksheet and it created many opportunities for discussion and debate!