The name creates the man?

A friend of mine I graduated from Palmer with had a son pretty soon after graduation. Her husband is a big fisherman (fly fishing), and when they found out they were having a son, her sister-in-law suggested Fischer, since her husband likes to fish. Well, we knew they had been pregnant again, but we never got a birth announcement. But when Christmas rolled around, we got a card with the pictures of their two sons. The second child is named Finnegan. Instantly, my thought went to nicknames for these kids... Fish and Fin.