While looking over my bookshelf, I picked up Lyndal Roper's Witch Craze and leafed through the chapter on the "godless children" of the early 18th century. It struck me that this might fit very well into the history of the Potterverse.
To summarize: in the early decades of the 18th century in Augsburg and other German areas, the general fears turned from old women as witches to children as witches. Parents reported that their children sprinkled shards of glass and devilish powders in their beds to sicken them, held witch's sabbaths, and played all manner of Satanic games (among other things). Many of these children ended up incarcerated in a hospital for years.
Now, from the reports, it sounds like many cases were just disturbed children from dysfunctional families. However, if we pretend that this is the Potterverse for a minute, the remainder of the cases may have some sound historical reason for happening. The wizarding world had retreated into secrecy and seclusion in 1689 (or 1691, depending on which JKR book you're reading - let's just say that the statute was written in 1689 and formally adopted in 1691). By the early 1700s, any wizarding children born in the Muggle world most likely would be cut off from any magical training. However, wizards had lived openly recently enough that stories about them would still be circulating. Some children - magical or not - could well try to imitate the spells they had heard about from their older cousins or aunts or whomever. Some of them might even have succeeded. Regardless, their parents would have worried.
Fortunately, the practice of executing witches had pretty much died down by now (with a very few exceptions). The children were eventually released, and most people agreed that the whole witch craze was perhaps a bit over the top. Belief in witches died down as (accurate) memory of openly practicing witches and wizards faded, and by the end of the century witches were little more than a fable to Muggles. Any magical children born in the Muggle world after that would only manifest magic spontaneously, not deliberately try to mimic traditions.
To summarize: in the early decades of the 18th century in Augsburg and other German areas, the general fears turned from old women as witches to children as witches. Parents reported that their children sprinkled shards of glass and devilish powders in their beds to sicken them, held witch's sabbaths, and played all manner of Satanic games (among other things). Many of these children ended up incarcerated in a hospital for years.
Now, from the reports, it sounds like many cases were just disturbed children from dysfunctional families. However, if we pretend that this is the Potterverse for a minute, the remainder of the cases may have some sound historical reason for happening. The wizarding world had retreated into secrecy and seclusion in 1689 (or 1691, depending on which JKR book you're reading - let's just say that the statute was written in 1689 and formally adopted in 1691). By the early 1700s, any wizarding children born in the Muggle world most likely would be cut off from any magical training. However, wizards had lived openly recently enough that stories about them would still be circulating. Some children - magical or not - could well try to imitate the spells they had heard about from their older cousins or aunts or whomever. Some of them might even have succeeded. Regardless, their parents would have worried.
Fortunately, the practice of executing witches had pretty much died down by now (with a very few exceptions). The children were eventually released, and most people agreed that the whole witch craze was perhaps a bit over the top. Belief in witches died down as (accurate) memory of openly practicing witches and wizards faded, and by the end of the century witches were little more than a fable to Muggles. Any magical children born in the Muggle world after that would only manifest magic spontaneously, not deliberately try to mimic traditions.