Understanding the conditions under which families try to influence members' health-related practices can provide information to build concepts adding to models of health promotion. This paper reports on an exploratory qualitative study examining the influences of intergenerational relationships in shaping beliefs, knowledge and practices about health and illness in a regional Australian city. We conducted semi-structured interviews with 27 adults with family members of other generations living in the city, all of whom had experience of asthma. We found that overall people's experience of health and illness, particularly in childhood, was taken for granted and not reflected upon. It was in the face of serious illness or death of a family member that objective knowledge about health and illness was sought and integrated within the family leading, in most cases, to significant lifestyle changes or ‘doing things differently’. We drew on Bourdieu's concept of the three forms of theoretical knowledge in analysing our findings. We found the concept of knowledge as ‘primary taken-for-granted experience’, and the concept of praxeological knowledge as the knowledge created by the dialectical relationships between an individual subject and objectives structures were helpful. To influence individual health practices, we need to acknowledge how the family context confirms the taken-for-granted health practices of an individual and the family circumstances that might lead families to seek objective knowledge and make lifestyle changes to promote health.