1 method give him an exotic slave and a mistress in his retinue. If that does'nt work there may be some problems as he has 3 avenues to take for a child.

Check his traits, if Spartan is one of then he's gay.

So if all else fails do the Braveheart maneuver. Heck if his dad made such a good son I'm sure there's a good chance he can do it again.