I've always questioned the sanity of the person who created the unspoken rule that the best socialization is found solely amongst one's peers - especially when those peers are first graders. I define truly successful socialization as the ability to get on with all people, regardless of age, race, ethnicity, or sex. Neither of my boys bat an eye at speaking to an elderly woman, a kid their age, or someone of a different race or religion. Liam even once struck up a basic conversation in Spanish with a fellow shopper at our farmer's market. I just crossed my fingers and hoped that he wasn't saying anything vulgar as I had no clue what was coming out of his mouth. Most homeschooling groups are incredibly diverse as well: my group counts Hispanic, black, Bosnian, Russian, and white families as members. Some are Christians, some are not, some are Republicans, others Democrats. It's a welcome change for me, someone who went to an average, all-white suburban school district. My socialization in school did not prepare me for the diverse world and were it not for the 15-plus years of ballet training with people of all backgrounds I would have experienced major culture shock when I hit college.
I don't think you need to stick a kid in an institutionalized setting to teach the virtues of sharing or taking your turn; that humanity accomplished such eons before public schools were established is testament to that. (Public education rather than homeschooling is the real new kid on the block as it's still relatively a new practice.) Plugging them into the vast world surrounding them sharpens their social skills more than you'd think."