Ichabod's mother magically foresaw her son's role in stopping the Headless Horseman.Why would a woman like Ichabod's mother marry a man like Ichabod's father? I get that opposites can attract, but there are limits. Consider the following alternative explanation: she magically foresaw the coming of a supernatural menace and also foresaw that her son by Ichabod's father would be instrumental in stopping the menace. She probably had no further details, so there was not much else she could do to stop the menace she foresaw. It may even have occurred to her that she was risking her life by marrying Crane, but she nevertheless decided to risk it in order to bring Ichabod into being. That may have been why she tried to start teaching him magic at a young age: she thought he would need magic to stop a supernatural menace.
WMG / Sleepy Hollow (1999)