I'd like to posit a theory: Christopher Plummer's DNA was frozen in 1965 and used to create Michael Fassbender roughly a decade later.
This theory may be controversial. After all, great lengths have been taken to create Fassbender's backstory and to provide him with "parents" and a conventional upbringing. In fact, it was in all parties' best interest to create a cover up. However, I am not afraid to bring it to the surface. I will risk any possible consequences and stand tall in the face of possible retribution to let the truth be known.
The loss of Christopher Plummer's frozen DNA was perhaps Canada's darkest day. A possibly crippling embarrassment, avoided only by the success of Project C (otherwise known as the Alan Thicke / Michael J. Fox Initiative) of the 1980's. The Great White North lost the genetic code of their award-winning native son when it was spirited out of the country and across the Atlantic to Germany. (Yes, of course it was the Germans. Did you really think anyone else could be responsible?) The German thirst to have their own master race of acting supermen was at a fever pitch during the Cold War.
And what better way to make their mark in the world of theatre and film than by finally making Captain Von Trapp their own. There would be no escape into the Alps this time. No singing. No hills alive with the sound of music. Now you see it. Now it's all coming together, isn't it? A plan, beautiful in its simplicity, covering all the bases. You say you want proof? Just use your own eyes and ears. It's right in front of you.
Listen to their speech patterns, accents, and delivery. This was possibly the Germans' greatest trick and most fascinating achievement. After years of study, they determined that pairing his German surrogate father with a surrogate mother from a specific area of Northern Ireland would create the perfect amalgam to mimic Plummer.
I realize they aren't identical. Cloning, after all, has never been an exact science. But it's there. Don't tell me you can't see it; particularly in the hair and furrowed brow. No, Fassbender may not have quite the schnoz that Plummer commands, but the gaze and posture say it all.
Watch the way the two actors carry themselves. Look at how they command the screen in every scene they appear in. Compare the militaristic Captain Von Trapp (pre-warmhearted, musical transformation) to David from Prometheus. Compare the suave Sir Charles Litton from the Pink Panther franchise to a character like Brandon from Shame (minus the full-frontal and sex addiction). Okay, the roles may not be an exact match, but this is clearly a Plummer career arc for the 21st Century.
Fassbender was "born" in 1977. He is now 35 years old. Approximately the same age as Christopher Plummer when he starred in The Sound of Music. The Germans' plan has come to fruition. Their Superman is fully matured. Be on alert people. The age of Plumbender is upon us. Prepare for his acting domination. You better believe a Hollywood producer is on the phone at this very moment, pitching a dark and gritty remake of The Sound of Music. I pray that we can all resist the inevitably charming results when he is paired with Anne Hathaway who has been waiting quietly; slowly stealing the voice and life force of Julie Andrews since they worked together on The Princess Diaries. But, that's an exposé for another time.