Why parents tell kids not to eat sweets

During my early primary school days, I loved to carry sweets and biscuits to school. Every time, my dad saw me with sweets, he would threaten to confiscate them.I habitually kept on eating sweets and hid them from my dad since I knew he didn’t like me eating them.I would never bother to brush my teeth after eating sweets because I was always rushing to play with my friends.