I have been wondering lately, is "Kerman" really a family name, after all ?
It would make much more sense as an honorific suffix, like "-san" in japanese or "-ssi" in korean. Under this hypothesis, Kerbals have only one, very colorful name, but the etiquette of the Kerbal society requires that they address each other by the name + "Kerman". Only Kerbals who have got to know each other closely, like Bill and Valentina stranded together for ten years in a Mun lander short of fuel, would dare to call each other by name only (a practice known as "kermansute").
Just thinking.