Religiosity
Religiosity, in its broadest sense, is a comprehensive sociological term used to refer to the numerous aspects of religious activity, dedication, and belief (religious doctrine).  Another term that would work equally well, though is less often used, is religiousness. In its narrowest sense, religiosity deals more with how religious a person is, and less with how a person is religious (in terms of practicing certain rituals, retelling certain myths, revering certain symbols, or accepting certain doctrines about deities and afterlife).

# Components
Numerous studies have explored the different components of human religiosity (Brink, 1993; Hill & Hood 1999). What most have found is that there are multiple dimensions (they often employ factor analysis). For instance, Cornwall, Albrecht, Cunningham and Pitcher (1986) identify six dimensions of religiosity based on the understanding that there are at least three components to religious behavior: knowing (cognition), feeling (affect), and doing (behavior). For each of these components of religiosity there were two cross classifications resulting in the six dimensions:
- Cognition
traditional orthodoxy
particularistic orthodoxy
- traditional orthodoxy
- particularistic orthodoxy
- Affect
spiritual
church commitment
physical
- spiritual
- church commitment
- physical
- Behavior
religious behavior
religious participation
- religious behavior
- religious participation
Other researchers have found different dimensions, ranging generally from four to twelve components. What most measures of religiosity find is that there is at least some distinction between religious doctrine, religious practice, and spirituality.
For example, one can accept the truthfulness of the Bible (belief dimension), but never attend a church or even belong to an organized religion (practice dimension).  Another example is an individual who does not hold orthodox Christian doctrines (belief dimension), but does attend a charismatic worship service (practice dimension) in order to develop his/her sense of oneness with the divine (spirituality dimension).
An individual could disavow all doctrines associated with organized religions (belief dimension), not affiliate with an organized religion or attend religious services (practice dimension), and at the same time be strongly committed to a higher power and feel that the connection with that higher power is ultimately relevant (spirituality dimension).  These are explanatory examples of the broadest dimensions of religiosity and that they may not be reflected in specific religiosity measures.
Most dimensions of religiosity are correlated, meaning people who often attend church services (practice dimension) are also likely to score highly on the belief and spirituality dimensions.  But individuals do not have to score high on all dimensions or low on all dimensions; their scores can vary by dimension.

# Genes and environment
The contributions of genes and environment to religiosity have been quantified in twin studies (Bouchard et al', 1999; Kirk et al', 1999). Koenig et al (2005) report that the contribution of genes to variation in religiosity (called heritability) increases from 12% to 44% and the contribution of shared (family) effects decreases from 56% to 18% between adolescence and adulthood.