Flash Gordon (2007 TV series)/WMG

Ming is Flash's father
First, Ming was revealed to be Caucasian rather than an Asian type.

Then there was a throwaway reference to time dilation between Earth and Mongo - enough for Ming's daughter to have been born after Mr. Gordon was trapped there.

Then there was The Reveal that Ming was chasing the youth vampire because she had been keeping him young. A Fountain of Youth is necessary for this theory, since Ming is {physically} younger than Mr. Gordon. It so happens that there is one.

The twist at the end of the 'trapped on Mongo' two-parter -- that the prisoner was lying about Mr. Gordon being executed -- makes this theory more likely.