My bet is they were hatchlings from the same clutch.
I have swans as regular visitors to my dock.
They are fairly common on Michigan lakes.
The males are very aggressive and drive off all contenders for space, food and family interference.
They must weigh 75 pounds, and are a formidable adversary for kayak or a jetski in a no wake zone.
This year we had 4 babies. The young from previous years seem to go off and restablish as their own flock for awhile, presumably until they find a mate.
Failing that, I imagine they remain as "family flock" until something better comes along.
Leave it to the media to assume they have a human failing.
How do you spell A-n-t-h-r-o-p-o-m-o-r-p-h-i-s-m??