Where does inheritance collide?

In object-oriented programming, inheritance is the mechanism by which one class, the subclass, automatically acquires the fields and methods defined by another class, the parent or superclass, so the two stand in an is-a relationship and shared behaviour is written once. Snyder's 1986 Encapsulation and inheritance in object-oriented programming languages examined how this reuse mechanism collides with the boundary a class draws around its own data, and later work on multiple inheritance describes the diamond problem, where a class inherits the same ancestor along two paths. The referent is a reuse relation between class definitions in a program, and it is not a biological transfer of traits, a legal transfer of property, or an economic flow of wealth.[1]

Unit

One subclass-to-superclass link in a class hierarchy

Recovery means

Not applicable

Measured by

Read from the class declarations and inheritance graph of a program, for example the depth of the inheritance tree or the count of ancestors

In genetics, inheritance is the transmission of traits from parents to offspring through genes carried in the reproductive cells, so that offspring resemble their parents in ways that follow regular statistical patterns. Building on Mendel's nineteenth-century laws, Badano and Katsanis's 2002 Beyond Mendel: an evolving view of human genetic disease transmission reviewed how real traits often depart from simple single-gene patterns, setting out the several modes of inheritance and the many-gene basis of most characteristics. A related quantity, heritability, measures how much of the variation in a trait across a population tracks genetic differences rather than environment, and Tenesa and Haley's 2013 The heritability of human disease: estimation, uses and abuses described how it is estimated and misread. The referent is a biological transfer of hereditary information across generations, and it is not a relation between classes in code, a bequest of property, or a flow of financial wealth.[2][3]

Unit

One allele or trait passing from parent to offspring across a generation

Recovery means

Not applicable

Measured by

Traced through pedigrees and breeding crosses, and quantified by heritability estimates from family or genomic data

In economics, inheritance is the intergenerational transfer of wealth: the assets that pass from one generation to the next by bequest and gift, studied for its weight in total wealth and its part in inequality. Piketty's 2011 On the Long-Run Evolution of Inheritance: France 1820-2050 reconstructed the flow of inherited wealth as a share of national income over two centuries and argued that it can return to dominate self-made saving when growth is slow relative to the return on capital. The referent is a flow of financial and physical assets between generations, valued in money and often taxed, and it is not a class hierarchy in software or a transfer of genes, and though it overlaps with the legal act of passing an estate it aggregates many such acts into one economic quantity.[4]

Unit

One bequest or gift of assets passing between generations, valued in money

Recovery means

Not applicable

Measured by

Estimated from estate and tax records and from surveys as the annual inheritance flow relative to national income or private wealth