Sisters, to me, are fascinating because it is a unique connection of the coming together of connection and competition. The fact that you have these age differences is a built-in power struggle, and the fact that you're all trying to get attention and resources from the same parents creates competition.
Conversations with sisters can spark extremes of anger or extremes of love. Everything said between sisters carries meaning not only from what was just said but from all the conversations that came before - and 'before' can span a lifetime. The layers of meaning combine profound connection with equally profound competition.
In a world of status, independence is key, because a primary means of establishing status is to tell others what to do, and taking orders is a marker of low status. Though all humans need both intimacy and independence, women tend to focus on the first and men on the second. It is as if their lifeblood ran in different directions.
When women told me they'd always wished they had a sister, they were thinking of this ideal of mutual encouragement and support. Many of those who have sisters also yearn for this ideal because their relationships with their sisters don't always live up to it.
Many mothers and daughters are as close as any two people can be, but closeness always carries with it the need - indeed, the desire - to consider how your actions will affect the other person, and this can make you feel that you are no longer in control of your own life.