I go to a top 20 school and have two non-traditional friends (mid 30's-40's). One of them excelled (law review, top of the class). When it came time for interviews, he had his pick. The other had terrible grades because he did not have enough experience with typing to keep up with everyone else during exams (he improved his typing, got better grades, and has a non-big law job doing exactly what he wants).
I think a key part of the equation is grades. I think that age can also be an advantage. You have a lot more on your resume, hopefully, than I do. Prior experience can help a lot in getting a job. Also, 30-40 year olds typically have their priorities in order. I would venture to say, and this may come off as a generalization, but most older students wouldn't go work at big law firms unless they were willing to do the work. Younger students often come into it with the mind set that they will work, pay off loans, then go do what they want. Older students often do not have to go this route and will only do it if its what they want to do. Now, that is just my impression, so people may disagree.
Also, as far as adults having kids, I would imagine it would be a selling point if a female candidate already had kids. You know then that she wont have to take time off to have them since they are already there.
If it is a career option you want, go for it. I dont think your age will play a role. Keep in mind though that the market sucks, grades are unpredictable, and the legal market in Boston is small. Dont go into it naive.