Inbred Descendants Of Time Travelers

Especially at the end of time travel crime, the descendants of time travelers ended up being inbred.

Basically, the time travellers ran out of new times, and replaced all the important people in the times they knew of. Their descendants later inter-bred with each other, producing inbred descendants of time traveling criminals on a scale never seen before.

OR

Sometimes, time traveling criminals' depredations against foreign planets were noticed by criminals from those planets, who, manuvering complicated combinations of ignorant legal, and criminal technology, basically used mind control and sensory replacement to cause the invading criminals to inbreed with others from their families, leading to the production of inbred children, who were already fully mind controlled from before their births. These inbred descendants of time traveling criminals were sometimes used to sap the technological resources of the criminal clans they came from, especially by issuing unwise commands that would lead their families and technology to be discovered by legal forces who could oppose them, or by stimulating wars with other time travelers, regardless of their affiliation. Either way, the mind controlled inbred descendants of time travelers were or are basically used to lead invading time travelers away from the foreign places they invaded.

See: Rudolph Grinch, Moff Tarkin, Giselle Schröder, Dieter Weber, Terra, Alderaan, Donald Fowler, Elizabeth Fowler, Landon Fowler (Rawling), Glossu Rabban, Giedi