(one) is old enough to be (someone's) (parent/grandparent)(redirected from he's old enough to be his father)
(one) is old enough to be (someone's) (parent/grandparent)
One is old enough to be someone else's parent or grandparent. Used in reference to two people who are or may become romantic or sexual partners, especially to indicate that the speaker thinks such a pairing would be inappropriate. He's going out with Mary from the legal department? But she's old enough to be his mother! I don't feel comfortable with this. I'm old enough to be your grandfather, for heaven's sake!
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.