Historically, families have usually had more children than parents, resulting in family trees that looked like pyramids. In recent years, though, especially in countries like Britain and the US, the number of children per generation has steadily gone down, while life span has increased. This has led to a shape of family tree that some researchers have likened to a beanpole — tall and thin, with few people in each generation. The term beanpole family has been around in the academic literature at least since 1987, but it rarely appears elsewhere. A recent British report has brought it to wider public notice, at least in the UK. Some researchers find it too slangy and prefer the jargon term verticalised to describe such families. Whatever term you prefer, specialists are sure that the demographic shift is having a big effect on personal relationships within the family and (for example) the role of grandparents.
The rising divorce rate partly explains the growth of the “beanpole” family. With almost one in two marriages ending in divorce, many adults have at least two families, each with a single child.
Observer, May 2002
Noting the rising number of so-called “beanpole” families in Britain (families with only one child), the report warns that a child without siblings “is starved of the companionship of family members of their own age ... [leading to] greater social isolation, with teenagers adopting a more selfish attitude to life”.
Guardian, June 2002