It's partly whether the parents take the time to make sure the kids are socialized, and partly selection bias. A lot of parents decide to homeschool their kids

It's partly whether the parents take the time to make sure the kids are socialized, and partly selection bias. A lot of parents decide to homeschool their kids precisely because the kids are having a tough time in school socially, whether it's from bullying or from mild or severe developmental disorders. In my experience, a much higher percentage of homeschoolers enter homeschooling with dyslexia or autism than you see in the typical public school classroom. A lot of parents choose to homeschool specifically because they don't want their child pidgeonholed and pipelined into special needs classrooms.