Getting the facts straight

Justin, Max, and I were putting together this puzzle. Justin was explaining the facts to him about horses, "This is a mother and baby horse. The baby horse is called a foal, and a girl horse is called a mare...She's the mother."

Max looked at me, then at the puzzle, then back to me with a look of TRUE CONFUSION. He said in a tone of total disbelief, "YOU MEAN TO TELL ME YOU USED TO BE A HORSE???"