Tim Drake was the son of criminal Steven "Shifty" Drake, a thug for the crime lord Two-Face. He had very little respect for his father, and often had to fend for himself. Around the age of 10, Drake began to idolize Gotham City hero Batman and placed newspaper clippings on his wall.
Robin did not become the Joker. The second Robin in the animated series, Tim Drake, was kidnapped by the Joker, tortured, and turned into a sidekick/pet of the Joker called Joker Junior. Batman rescued him, but he was so traumatized that he quit being Robin.
DC has made it common not to give The Joker any solid backstory or family, but they still managed to accidentally give him a son. Due to DC canceling a comic just a bit too early, they unintentionally left Joker with a son in the form of Lonnie Machin, also known as Anarky.
Duela Dent frequently appears in the Tiny Titans series as the Joker's Daughter. She often antagonizes Robin, who informs her in Tiny Titans #17 that there are no clowns allowed at his birthday party.
Joker Jr. was born after The Joker, who had manipulated Harley Quinn into re-entering a life of crime, impregnated her without her knowing. Harley out of shame refused to accept the child and gave him up. He grew up being transferred from various orphanages and foster homes to people who never loved him.
The series ended in controversy when the final issue suggested that Anarky was the biological son of the Joker. Originally a suggestion by Norm Breyfogle, the idea was advanced by Alan Grant as an attempt to solidify Anarky's role as a part of the Batman mythos.
In Injustice: Gods Among Us, Harley Quinn reveals she gave birth to Joker's daughter, but gave her up for adoption rather than subject her to a life with Joker as a father. Similarly, Harley becomes a mother to twin children in the Batman: White Knight universe, though with happier results.
In Batman: Curse of the White Knight, Harley becomes pregnant by Jack Napier, the cured version of Joker, and in Injustice: Gods Among Us, Harley carries non-cured Joker's baby, but hides her away from the Clown Prince of Crime.
Harley reveals to Black Canary that she has a four-year-old daughter named Lucy who is being raised by her sister. After discovering she was pregnant, Harley left the Joker for almost a year to have their baby instead of abortion.
Later, Arthur goes to Arkham State Hospital and steals his mother's records, and finds out that he was in fact adopted, and that Thomas Wayne is not his father and that Penny is not his true mother.
No, none of the Robins are biologically related to Joker. In comics, Joker has never been shown to have any relation to Richard Grayson, Jason Todd, Tim Drake, Stephanie Brown, Damian Wayne, Carrie Kelly, or Matthew McGinnis. However in the DCAU, Joker did kidnap Tim Drake and turn him into a Joker Jr.
when he was kidnapped by the Joker, Drake was implanted with a microchip that encoded the Joker's DNA with nanotechnology, into him. Over time, the Joker resurfaced and periodically assumed control of Drake's body. The second Batman, Terry McGinnis, deduced Drake's connection and confronted the Joker.
On this month's Waiting on the Trade, we discussed Batman: A Death in the Family, the landmark story in which the Joker brutally murdered the second Robin, Jason Todd.
It is then revealed that the Joker's real name is "Jack Oswald White." Martha then shares that she visited the Flashpoint universe's version of Jack Oswald White, discovering him to be a struggling family man supporting his wife and a child as a janitor at Wayne Casino.
"When Poison Ivy decided to change her ways and continue her plant experiments, she created Sporelings, human-plant hybrids with her unique powers. She successfully grew two Sporeling babies, Rose and Hazel, nurturing them in her apartment.
In Countdown #50, Jimmy Olsen interviews an incarcerated Joker about the murder of Duela Dent, who had called herself the Joker's Daughter. The Joker states that he never had any daughter, and expresses awareness of the Multiverse's existence and of shifts in reality. The Joker appears as he did before Batman #655.
The comics series The Joker: The Man Who Stopped Laughing features Batman's nemesis get pregnant after a curse is placed on him, Daily Mail reported. Eventually, the Joker "vomits a sort of brown goo" that transforms first into a baby boy and then into a mini version of himself.
Though Zatanna's backward spell, “On eno esle lliw reve evah ruoy ybab!” (“No one else will ever have your baby!”), backfires and the Joker wakes up to discover he is nine months pregnant. Suddenly going into labor, the Joker vomits with the ejected matter morphing to form a mini Joker.
Jeremiah Valeska is a major antagonist in the television series, Gotham. He is the twin brother of the terrorist cult leader, Jerome Valeska, as well as being the arch-nemesis of Bruce Wayne. Jeremiah is the show's equivalent to the Joker, taking over from Jerome, although both of them never took on the Joker alias.
Batman: Beyond the White Knight has a startling segment where Harley's daughter walks into their apartment and bares a shocking resemblance to her father, the Joker.
One of the mysteries in director Todd Phillips' Joker is whether Arthur Fleck really is the son of Thomas Wayne as his mother Penny Fleck claimed. Both Wayne himself and Alfred Pennyworth said it was untrue and that Penny was delusional, hence her eventual stay in Arkham Asylum.
