Gyllenhaal met the actress when she was shooting 1988 movie Running On Empty, which was penned by his screenwriter mother Naomi Foner.
He was instantly smitten and credits the encounter with developing his desires for the opposite sex.
The single star tells GQ magazine, “I had such a huge crush on Martha Plimpton. I remember sitting with her. I must have been five or something like that. I mean, she was just strong and beautiful. That is when I remember falling in love with girls.”