I recently read about a study that found siblings have a big impact on a child's social development. It was of interest to me because as the parent of a single child, I often wonder if he's missing out.

The study by a University of Illinois researcher found parents teach children the formalities of how to behave around others. Siblings are better role models for informal social behaviors, like how to act cool in front of your friends. In other words, you teach your child how to say "please" and "thank you" while his brother teaches him how to talk to girls.

The study found single children are more likely to develop social skills through friends. So preschool and play dates go a long way to help only children develop social skills.

We can see Kellan's social world opening up more and more. He is less shy about approaching kids he doesn't know. He's also more willing to initiate play or conversation. While we were on vacation, Kellan found two kids he liked and played near them. Soon they were running around the beach together.

How do your children relate to each other? If you have a single child, how does he socialize with other kids?