are all ages accepted ?

Most chapters have older girls, GPhi even at one point had a mom & daughter at the same time. Girls who were in their 30's even went through recruitment. Chapters aren't allowed to discriminate on age.
But if you're in your late 20's, why would you even be interested in hanging out with a bunch of girls who are mainly fresh out of high school. Imagine being in a pledge class where other girls are 17,18, and 19. Even most senior/ junior girls are only 21/22. Do you really think you could relate to them?

This is a hard question. In theory there is no age limit. And in a perfect world there would be no age discrimination, but there kind of sort of is. That said, more and more chapters all over the country have people even in the 50s going through rush and its becoming a lot more common. If you really want to do it, I say go for it.