Nope, not really. The first time he was mentioned (with was also the Nephews de facto debut), he was hospitalized after a prank involving fireworks in a chair.
As for their mother, Della, it was somehow explained in a comic book story 80 is prachtig from 2014, which was released to celebrate Donald's 80th anniversary. According to that story, she was an astronaut. She left then baby Nephews in Donald's care before a trip to space… one that she never came back from. Damn.