They don't care AT ALL about how you did, OP. They care that you value your experience such that you want your child there as well. And even more, they'd love it if you donated 10M+. That would bump up your kid's chances from mere legacy (which isn't much at all) to development: and that counts for a lot more!

I don't think they are looking up your GPA. But I do think annual giving and alumni involvement makes a difference.

Is your name on a building

I keep hearing that legacy status matters. I went to a Little Ivy but graduated with a bad GPA (B- average I guess? I failed a course.). Does it help my kid to have me as a parent alum?