According to Marmot’s theory of social determinants of health (2005), poor health and risky health related behaviours are not only associated to genes but they also involve the circumstances in which people live. In this research project, we take into account one element of this set of circumstances: the family. Indeed, family has been not only considered as the basic unit of society but it also represents an important place for the individual growth. The aim of this research project is to provide a rigorous and systematic statistical based analysis of how family affects individual's health related behaviours across the life-course. Since the project focuses on three different aspects of health related behaviours depending on age, we structure the work into three different articles. The first investigates the impact of family structure and the amount of time and the typology of daily-life shared activities among family members on offspring’s overweight at 5 and at 10 years old. The second article analyses the relationship between having siblings and teenager’s sexual behaviours, whereas the third article investigates maternal transmission of health related risky behaviours at age 34 (smoking, drinking and being obese). Data are drawn from the 1970 British Cohort Study (BCS70).