After that the Danites set up the carved image for themselves, and Jonathan the son of Gershom, the son of Moses, and his sons became priests to the tribe of the Danites until the day that the inhabitants of the land went into exile.
~Judges 18:30

Moses’s grandson, Jonathan, descended from the most famous Levite, but Jehovah had installed Aaron’s descendants as those primarily responsible for carrying out the priesthood (Nu. 3:3,6,9,10).

On top of this, Jehovah had forbidden the use of idols in connection with his worship time and again (Ex. 20:4; De. 4:16; 5:8).

It was selfish of Jonathan to allow the man from Ephraim to install him as priest, leading his family in idol worship in exchange for money (Jud. 17:10).

His selfishness is magnified by his later betrayal of that family to go serve as priest before the tribe of Dan, collaborating with the Danites in their theft of various expensive idols (Jud. 18:18-20).

What can I learn from Jonathan’s attitude?
Even if I were to come from a family with a rich spiritual heritage or certain level of prominence, I should not assume my family’s reputation automatically makes me a spiritual person.
No one is exempt from following God’s explicit laws or practicing his principles, regardless of what their last name may be.
Each person is ultimately responsible for upholding strong Biblical values wholeheartedly on an individual basis (Ez. 18:30).