You won't find a better "school of life" than being part of a big family.
Most behavior is learned, and a child’s emotional education begins at home. Children learn emotional maturity as the adults in their life teach and practice with them. They need the freedom to say what they like or dislike, and they need to be encouraged to start conversations and games with other children.
Parents should always keep in mind that children learn little by little, step by step. The skills involved in emotional maturity will not only help them do well in school and make friends, but will set them up for success in life.
Families with more children have the advantage in this regard because of the amount of affective, relational, and cognitive stimuli each member of the family experiences each day.
From their very first year, children are interested in getting to know the people around them. Their instinct to play begins in the first few months and grows over the years — largely stimulated by their siblings. It’s like a school of life: They get a head start on social and affective development, since they have to learn to manage their emotions with siblings of different ages, interests, and personalities.