It is natural not to care about a sister, certainly not when she is four years older and grinds her teeth at night. Gertrude Stein
Sisters is probably the most competitive relationship within the family, but once the sisters are grown, it becomes the strongest relationship. Margaret Mead
Sisters define their rivalry in terms of competition for the gold cup of parental love. It is never perceived as a cup which runneth over, rather a finite vessel from which the more one sister drinks, the less is left for the others. Elizabeth Fishel
A sister is both your mirror – and your opposite. Elizabeth Fishel