Donald Sutherland has a much longer face than Kiefer. However, they both give off nearly identical vibes. They're warm & gravelly when playing good guys; downright terrifying when playing bad guys. And I think if Kiefer went on a starvation diet (think Christian Bale in
The Machinist), he'd look almost exactly like Donald.
David Troughton can look a lot like Patrick Troughton.
They've got the same eyes, the same lines around the mouth, the same imperious expression. Put a black Beatle wig on David and you wouldn't see any difference at all. However, I don't think Sam Troughton has much of a resemblance at all.

He probably takes after his mother.
Emilio Estevez and Charlie Sheen both look like Martin Sheen... but don't look like each other.
I dunno. I think that Emilio & Charlie have a certain resemblance to each other. Before I knew they were related, I remember watching
Terminal Velocity and thinking, "That guy looks a lot like the guy from
The Mighty Ducks."
As for how much they look like Martin, I'd say that Charlie looks like Martin when Martin is playing super-serious & dramatic. Emilio looks like a more casual, less intense Martin.
Will Smiths kids look like him and Jada.
Jaden Smith is too old to really make a determination about appearances. However, I could hear a lot of Will's cadences during Jaden's performance in
The Karate Kid.