The long wave in your beard, just like the straightness of your scalp hair, is genetic and not a result of your grooming techniques. The symmetry of your beard's wave is impressive.

It is not unusual for a man with straight scalp hair to have some curliness or waviness in his beard. However, for cultural reasons, it seems most men these days who carry the long-wave-beard trait either shave too much of their faces or do not grow their beards long enough to show it.

Further length may or may not cause the wave to repeat.

Any straightening method will require some maintenance.