I just looked up her current status and I never realized she was so close to my parents' ages! She was born in '39 and I'm not sure why I was thinking she was at least a decade younger than that. She was over 30 when Love Story came out.
It's hard to find pictures that show the resemblance. I saw the Drew Barrymore show, and on there, it was more apparent - even the mannerisms and the way Katie expressed herself.