Britney Spears‘ ex hubby has just been voted the 7th most influential man under 45 by Details Magazine, People Magazine reports. Kevin Federline shares his No. 7 spot with the late Anna Nicole Smith‘s flame Larry Birkherd, under the category “The Good Fathers,” whose nominations the mag explains this way: “by being more visible presences in their children’s lives than many Hollywood A-listers, they emerged as unlikely candidates for Dad of the Year.” The 29-year-old told the magazine, “To be a father is