Something like this can help-
SELECT E1.Firstname, E1.Lastname, E1.DOB, EmpID , [State] ,City
FROM Employees E1
INNER JOIN
(
SELECT Firstname, Lastname, DOB,COUNT(Firstname)
FROM Employees
GROUP BY Firstname, Lastname, DOB
HAVING COUNT(Firstname)>1
) AS E2
ON E1.Firstname=E2.Firstname AND E1.Lastname=E2.Lastname AND E1.DOB=E2.DOB
In case, you need further help please let me know.
Hope, it helps :)