When I was younger, I wondered if possums were Irish immigrants, dropping the "O" in opossum to Americanize their names. Unfortunately, that astute theory was untrue, as opossums originate in North America. Drat! Possums are not considered great pets; you don't need an animal scientist to figure it out. The best way to determine if an animal is suited to be a pet is to watch how your mom reacts to seeing one while driving in the car. Dog? Oh yeah, for sure, a pet. Horse? You better believe that…