This study investigates the influence of the male breadwinner norm on fathers' decisions regarding childcare responsibilities. We study the complex interplay between economic factors and gender norms in shaping the division of household labor within families by analyzing the impact a breadwinning mother has on fathers' choices regarding paternity leave (fully subsidized) and parental leave (partially or not subsidized). We exploit administrative data, provided by the Italian National Security Institute (INPS), including demographic and working characteristics of both parents together with information on the use of paternity and parental leave by fathers in the 2013-2023 period. We find that, in line with the "doing gender" hypothesis, when the leave is fully subsidized, as for paternity leave, fathers are less likely to engage in childcare when their wives earn more than they do. In contrast, this dynamic does not apply in cases of parental leave, where the economic costs of aligning with the gender norm are substantial. The effects we find are robust when replacing the actual probability of there being an out-earning mother with the potential probability and are amplified by the salience of the gender identity norm.