5 foot 4

Every morning when I wake up I rush to the door frame of my bedroom, place a pencil over my head and draw a mark on the wood. I quickly draw out a measuring tape and calculate the distance from the floor to the mark. Five feet, 4 inches. This has been the same result every morning for the past 15 years but I keep checking. My mum is 5'4, my dad is 5 foot 8! Why am I cursed to live in this tiny body?