Marvel's Avengers: Everything You Need To Know About M.O.D.O.K.
5. He Has A Son
Before he became a supervillain, George Tarleton impregnated a girl called Linda Madigan. Tarleton abandoned her when he learned about the pregnancy. As his son, Sean, grew up, he became resentful of the father he never knew for breaking his mother's heart. But when Sean learned his dad was the infamous terrorist, M.O.D.O.K., he vowed to destroy him.
He tracked M.O.D.O.K. down and placed a bomb in his hoverchair before teleporting him to the middle of Times Square. Madigan contacted A.I.M. and told them that M.O.D.O.K. was intentionally performing a poorly co-ordinated attack on Times Square, proving he wasn't worthy to rule the organisation. Madigan framed his father, hoping he could swoop in and reform A.I.M. to fit his own vision.
Thankfully, the bomb on M.O.D.O.K. was stopped by Carol Danvers and Madigan was gunned down by A.I.M.'s Scientist Supreme. At the end of this story, we see A.I.M. scientists inserting Madigan's skull on an android's body.
They then discuss how they will turn Madigan into A.I.M.'s cybernetic minion called Head Case. However, since Madigan hasn't been mentioned in 13 years, it's safe to assume A.I.M.'s project to resurrect him fell apart (or the writers just forgot about it).