赫敏生於麻瓜家庭是如何進入魔法世界的？

According to the novels, admission to Hogwarts is selective, in that children who show magical ability will automatically gain a place, and squibs cannot attend the school as students (though they can work there in other roles, as Argus Filch does). A magical quill at Hogwarts detects the birth of magical children and writes their names into a large parchment book, but there is no admission test because "you are either magical or you are not." Every year, a teacher checks this book and sends a letter to the children who are turning eleven.

大致意思就是，具有魔法能力的人會被自動選出，啞炮就不行了。一支羽毛筆會自動寫下他們的名字。每年，老師會看這張羊皮紙並且通知那些已經到達年齡的學生。
當她被選中的時候，應該會被引導進入魔法世界。包括她的父母，也是可以進入對角巷的。