Complex sentence: Parents that have dependable friends and formal group affiliations see positive effects in their children's ability to develop a friendship network, adjust to school, and build social skills while those without have children who are more likely to be restricted in their interests and activities.
Split into simpler sentences: Parents that have dependable friends and formal group affiliations see positive effects in their children's ability to develop a friendship network, adjust to school, and build social skills. Parents without dependable friends and ties to formal organizations have children who are more likely to be restricted in their interests and activities.