Interactions and relationships between sisters and/or brothers. The concept also applies to animal studies.

Persons or animals having at least one parent in common. (American College Dictionary, 3d ed)

A family composed of spouses and their children.

Works containing information articles on subjects in every field of knowledge, usually arranged in alphabetical order, or a similar work limited to a special field or subject. (From The ALA Glossary of Library and Information Science, 1983)

Affection; in psychiatry commonly refers to pleasure, particularly as it applies to gratifying experiences between individuals.

The sexual union of a male and a female, a term used for human only.

Activities designed to attract the attention or favors of another.

Any observable response or action of an adolescent.

The reciprocal interaction of two or more persons.

Achievement of full sexual capacity in animals and in humans.