Clarification on mothers and adult children of mothers in movies

Angela Lansbury was born in October of 1925, which means she was about 37 when The Manchurian Candidate came out in 1962, and Laurence Harvey, who played her son, was three years younger.

North by Northwest came out in 1959, which would make Cary Grant 55. Jessie Royce Landis, who played his mother, was eight years older than he was.

Amy Poehler talked (in some video I can't find) about the age difference between her and Rachel McAdams who played her daughter in Mean Girls. Poehler was 33 in 2004 and McAdams was 26.

Speaking of North by Northwest, the second half of this episode of Selected Shorts  is a pretty great story called Cary Grant's Suit.