A family of fractions

Faith is working on fractions at the moment, and had to write about our family using, what else? Fractions. Here it is:

Half of my human family are boys. A third of my family are girls. A forth of my family are mamals. One fifth person in my family is an animal that lives under water. 3 out of 5 people in my family have curly hair. One fifth in my family has a tail. 4 fourths like to swim. 1 fifth likes to build dinosaur traps.

Yes, she included our fish in the family. Who else would have a tail? I leave you to figure out who builds the dinosaur traps.