It was the patrons who funded, enabled, and occasionally directed the movement towards realism and secular subjects, and developed the genres.
genre
A bloke leans over the back of a seat in a railway carriage, trying to chat up a young woman who is just returning from a funeral. Is this an early Prussian problem picture?
His later portraits and domestic genre paintings grew lighter, and gave insight into home life at the time. His portrayal of fabrics is outstanding.
He innovated with full-length portraits, then from those developed domestic genre scenes which influenced Vermeer. He was born 400 years ago this month.
In the absence of any clearly articulated theoretical statements from the core French Impressionists, there are no obvious rules or clear criteria handed down.