Yes, this is typically the kind of deformations than must be fixed by setting up influences . But you must do this on a model that is fully boned ! BTW, if you add a bone going from the hip to the head to your stick man, you should notice less deformation, or even not at all . So, i'd suggest to set your bones right first, and then we can talk about influences, depending on the problems you'll have then . Oh, and no this doesn't come from booleans, at least i doubt it .