Continuing our background on BTTF, Marty is friends with one Emmett Brown, (Christopher Lloyd) local brilliant eccentric inventor. Doc has no family and Marty has no father to speak of. Their friendship is quite touching as Doc is Marty's substitute father figure, but it is ultimately not enough.
(Quick quiz: Did Lloyd and Fox, who had such amazing chemistry together in this trilogy, ever reunite to act together again?)
Fast forward to the end of the movie. Marty has changed everything by getting George to punch Biff while defending Lorraine. George's show of courage by standing up to whom he was most afraid – Biff – has informed the next 20 years of his life, making him a financial success, an inspiration to his children, and even a published author in his spare time. Their two oldest children are confident professionals. And Lorraine has blossomed into a lovely vivacious athletic woman, truly in love with her husband and her life.
The Father Makes or Breaks the Family
(Answer: Yes: Spin City in 1999 and The Michael J Fox Show in 2014. Full disclosure, I have never seen either show but found this info on Wikipedia.)