These days, the "father" role in many households is filled by a stepfather. It's hard to generalize about the influence of these men on their stepsons. A lot depends on how strong the birth father's relationship is with his son, how long the stepfather has been in the picture, and how active a role the stepfather takes in parenting his stepson.
From personal experience, I can testify that my son's birth father was his primary influence in many areas. In financial matters, however, Aniel quickly learned that his stepfather was the wisest and best-balanced role model. He now emulates his stepdad not just in money management, but also in his leanings toward a writing or academic career. Sometimes the impact of a stepfather's influence just isn't predictable.