Another case from America

No, I don't think for a moment that many children are living in these conditions, home educated or not, but this article gives you some idea of what professionals worry about when children are completely out of sight. It is unlikely that these four would have been unobserved, had they been attending nursery or school. It is also probable that if they had had to register as home educators and accept a visit, it would be hard to disguise the conditions under which they were living:

http://www.ottawacitizen.com/news/Boys+seized+from+Denver+home+malnourished+without+speech/9009170/story.html