The thing about timelines is that if one is disrupted, there are only ever a handful of people who will notice.
Perhaps a small group of Beatles fans who suddenly live in a world with no Beatles music, an egotistical weatherman, or a couple of teenagers and the weird old scientist they hang out with.
When Marty McFly returns from his trip to the past in which he DEFINITELY screws with the timeline, things are a bit different — especially with dear ol' dad, aka George McFly.
Besides the fact neither his mom nor dad notice their child looks exactly like their old friend Calvin Klein, George has a completely different vibe about him. He bosses Biff around, exudes confidence, and even encourages his son's music.
He's also published his first novel, called... what?