Let's say your kid is "weird" - on the autism spectrum, or ADD, or has severe allergies, or whatever. That can often cause problems in school, because children are often cruel. Parents of such children may be more likely to homeschool them than parents of kids that better fit the "normal" pattern.
Let's say the kid turns out a little weird. Would they have turned out better going through the public school system?
It's not necessarily fair to blame the homeschooling if the kids come out different. What were they at the start?
I think the view that homeschooled kids are weird is caused less by homeschooling and more by the fact that weirdos are more likely to homeschool.