In summary, while both Baumrind et al. (2002) and Beckett (2005) argued that we are not in a position to presuppose a clear causal link between corporal punishment (particularly parental smacking) and adverse child outcomes, the results of the twin study conducted by Lynch and colleagues (2006) are an early indication that a causal link may exist. There is still some debate about how well existing research distinguishes between severe physical abuse and physical discipline such as smacking, but current research efforts are looking to distinguish these behaviours more clearly (Ferguson, 2013; Lynch et al., 2006).