Solution: If you take 20 15 as the base, your father was born in 1968, his age is 20 15- 1968=47, and his mother's age is 47-4=43. Grandpa's age is 47×2=94 years old, and grandma's age is 94-6=88 years old.

Xiaohong is much older. The same zodiac sign means that the age difference between Dad and Xiaohong is an integer multiple of 12, that is, 47- 12=35 years old. This answer is impossible. Dad 12 years old has not developed well, so it is estimated that he can't have children. Ha ha! ! There are also 47-24=23 years old and 47-36= 1 1 years old, which should be the only two possibilities.

Dad and Xiaohong are monkeys, mom is a mouse, grandpa is a chicken and grandma is a pika.