Senator Flávio Bolsonaro, son of former President Jair Bolsonaro, heads seven of Brazil's eight most recent national electoral polls, according to a compilation published yesterday by Brazilian media Poder360. However, the differences between studies and margins of error keep open the dispute with President Luiz Inácio Lula da Silva over the country's presidency.The second round, scheduled for October 25, will face two candidates who arrived pra…