Like Serena Williams with older sister Venus, like Pedro Martinez with older brother Ramon, Jesse “Bam” Rodriguez started out as the younger sibling who tagged along.It was his brother Joshua Franco, older by four years and three months, who first wandered into the San Fernando Boxing Club in downtown San Antonio, and Rodriguez—full name Jesse James Rodriguez Franco—all of nine years old at the time, went along with him.“If my brother didn’t try it and like it, I would never even have watched a boxing fight to this day,” Rodriguez, now 24 and a champion in two weight divisions, said last week during a break in training. Rodriguez’s main interests at age nine were school and skateboarding. But after watching his big brother do his…