National Siblings Day takes place on April 10, 2015. It's a day of celebration and recognition for brothers and sisters. Siblings Day can be celebrated by sending a card or gift or making a dinner invitation to your siblings. The day was established by Claudia Evart after losing both of her siblings early in life. She has chosen April 10, the birthday of her late sister, Lisette.
A sibling is one of two or more individuals having one or both parents in common. A male sibling is called a brother, and a female sibling is called a sister. In most societies throughout the world, siblings usually grow up together, facilitating the development of strong emotional bonds such as love, hostility or thoughtfulness. The emotional bond between siblings is often complicated and is influenced by factors such as parental treatment, birth order, personality, and personal experiences outside the family. (With material from: Wikipedia)