Hi and welcome to Just Answer!
Please find rules for claiming a dependent in IRS publication 501 page 12 - http://www.irs.gov/pub/irs-pdf/p501.pdf
I put extract here for your convenience
So - generally your adult son, his wife and their two children may be your qualifying relatives if you provide mor ethan half of their support. They are not required to live with you.
You have equivocated: you have used the words: generally and may. Please clarify.
Are you still there?
I posted above tests to be your qualified relatives - I suggest you to reveiw these tests and verify if all are met.Let me know if you need any clarifications regarding these tests.
Tests To Be a Qualifying Relative
The person cannot be your qualifying child or the qualifying child of any other taxpayer.
The person either (a) must be related to you, or (b) must live with you all year as a member of your household (and your relationship must not violate local law).
The person's gross income for the year must be less than $3,700.
You must provide more than half of the person's total support for the year.
Please let me know if you need any help with these tests.
First you state that they are Not Required to live with me. Then under Tests To Be a Qualifying Relative.
The person either (a) must be related to you, or (b) must live with you all year as a member of your household - since your son is related to you - he is not required to live with you to be your qualified relative. But other tests should be verified as well.