Internet gambling websites are taking bets on who will the father of Britney Spears' next child. The TOXIC singer is mother to seven-month-old JAYDEN JAMES and 19-month-old Sean Preston with estranged husband Kevin Federline. Gambling site has given model ISAAC COHEN, who briefly dated Spears earlier this year (07), high odds for becoming the father to her next baby. Federline follows close behind at number, while Hugh Hefner and oil heir BRANDON DAVIS have been named as outsiders, reports.