Get a random date of birth specifying the age and with 6 months before birthday date?

How to get a random date of birth, specifying the age required and the generated date should be 6 months before the birthday.
Example: Want a date of birth for a person with 25 years that would have his birthday not before 6 months from now.
so if is generated today, could be 21/11/1995.
And then insert this date into 3 different boxes, 2 digits for day, 2 digits for month and 4 digits for year.
What's a solution? thanks