In the Star Trek: Voyager episode "Blink of an Eye", Voyager is stuck in orbit of a planet with a tachyon core which causes time on the planet to elapse at a much faster rate than normal.
Voyager's visible presence has a great effect on the planet's culture and technology, as centuries pass on the surface below. Eventually, the Doctor is sent down to the planet to investigate. He was intended to only spend 48 hours there, but ends up spending three years.
The inhabitants of the planet send up their own astronauts to Voyager, and the Doctor has the following conversation with the one who survives:
EMH: Find out what happened to a boy named Jason Tabreez. He lived in the Central Protectorate.
GOTANA-RETZ: Jason? An unusual name.
EMH: Yes. He was my son.
GOTANA-RETZ: But you're a hologram.
EMH: It's a long story.
This naturally leads to the following question:
How was the EMH able to have a son?
Presumably, Jason's mother is Mareeza (a woman the Doctor describes as his roommate and "companion" on the planet) but how was Jason fathered? What was the long story ?