Family Tradition.
1980
…
Sirius wouldn't have met his brother, but Regulus had insisted on a meeting and Sirius had run out of excuses. He refused to go back to the house. His brother understood and suggested they meet at the Leaky Cauldron.
"I've commissioned a picture of mama," was his news.
Sirius hadn't been able to bring himself to present any arguments against the idea. It was a family tradition, like killing the house elves, and Regulus wouldn't believe that they didn't need another her.
"There isn't any room in the picture gallery," was his argument.
"We can hang it in the hall."